Black Granite: Where It Comes From and Why It Is Not Really Granite

Black granite is one of the few stone categories where the name on the purchase order and the rock in the container are two different things — and where that gap is not a problem, a substitution or a trick, but simply how the trade works. If you import black stone, the geology behind the name is not academic. It decides how hard the material is, how it takes a polish, how much of a quarry's output can be cut into large slabs, how heavy your container is, and how stable your supply will be over the next five years.

This page is for importers, fabricators and project buyers working in container volumes. It explains what the material sold as black granite actually is, where the black colour comes from, why the polished surface behaves the way it does, and how the geology of four reference materials — two from India, two from China — translates into things you have to write into a specification. It is not a geology lecture. Every section ends in something you can put in a purchase order or a question you can put to a supplier.

One distinction up front, because it runs through the whole page: "black granite" is a commercial category, not a mineralogical description. The rocks sold under that name are usually not granite in the geological sense. That is not a defect and it is not a naming abuse — the ASTM dimension stone standard explicitly permits it. What follows explains why, and what it means when you buy.

Black Granite Origin: Why the Trade Calls It Granite When Geologists Do Not

True granite is a specific rock. It is composed of quartz, light-coloured feldspar and mica, and because those minerals are pale, granite is typically light in colour — the greys, whites and pinks that most people picture when they hear the word. A geologist looking at a polished black slab and being asked "is this granite?" will usually say no, and name a different rock.

What is actually sold as black granite is, in most cases, a dark mafic igneous rock: dolerite (also called diabase), basalt, or gabbro [source: stonecrestinternational.com]. Black Galaxy from India is a gabbric anorthosite. Shanxi Black from China is a gabbro-diabase. G684 Fuding Black is a basalt. Different rocks, one trade name.

The reason this is legitimate rather than misleading is a standard. ASTM C119, the American standard terminology for dimension stone, allows these dark igneous rocks to be quarried and sold under the name "black granite" [source: stonecrestinternational.com]. The standard reflects how the industry actually works: a stone merchant sells material by its appearance and working characteristics — dark, hard, polishable, durable — not by its petrographic classification. "Black granite" is a description of a product family.

Where the line sits, and where it does not. It would be wrong in one direction to say that black granite is granite, and wrong in the other to call it fake granite. Neither statement is the fact. The fact is that commercial naming and geological naming are two separate systems, and ASTM C119 is the bridge between them for this family. A supplier who tells you "it is not really granite, it is dolerite" is not undermining their own product; they are giving you better information than the one who simply repeats the trade name.

Why this matters commercially. Three reasons, and they compound:

"Granite" in a specification does not fix the rock type, so it does not fix the properties. Two materials both sold as black granite can differ in hardness by more than two points on the Mohs scale — from roughly 4.5 to roughly 7. That is the difference between a stone that needs care in a kitchen and one that shrugs off daily abrasion.
Rock type drives the physical data you need — density for freight arithmetic, water absorption for sealing and exterior exposure, hardness for wear.
Rock type drives supply behaviour, because it determines how the material occurs in the ground: as a small intrusive body, as a lava flow, as a dyke field. That in turn determines whether a quarry can scale, and how concentrated your supply chain is.

The practical instruction is short: do not treat the trade name as a material specification. Establish the rock type and the quarry, then buy against test values and a physical sample.

Basalt vs Granite: What "Black Granite" Actually Is

The materials under this name belong to the same broad family — dark, mafic, igneous — but they are not the same rock, and the differences are not cosmetic.

Material sold as black granite	Rock type	Origin
Shanxi Black	Gabbro-diabase	Hunyuan, Shanxi, China
G684 Fuding Black	Basalt	Bailin, Fuding, Fujian, China
Absolute Black	Dolerite / diabase / microgabbro	Karnataka, India (Dharwar Craton)
Black Galaxy	Gabbric anorthosite	Chimakurthi, Prakasam, Andhra Pradesh, India

Basalt, dolerite and gabbro are closely related — they share the same dark mineral suite and are separated mainly by grain size and by where the magma solidified. Basalt is the fine-grained variety, dolerite sits in the fine-to-medium range as a shallow intrusive rock, and gabbro is the coarser intrusive equivalent. This is exactly why the family was lumped together commercially: they look similar when polished, and they are all hard enough and tough enough to be worked as dimension stone.

The spread of properties inside one trade name is the buying fact of this category. Shanxi Black has a Mohs hardness of about 7. Black Galaxy has a Mohs hardness of about 4.5. Both are marketed, in ordinary trade usage, as black granite. A buyer who treats "black granite" as one material with one set of properties will eventually be surprised by a delivery.

Black Granite Formation: Three Minerals, One Colour

There is no dye and no pigment in natural black stone. The darkness comes from the mineralogy, and it comes from three contributors working together [source: stonecrestinternational.com]:

Calcic plagioclase feldspar. In true granite, the feldspar is rich in sodium and potassium, and it is pale. In these dark rocks, the feldspar is calcium-rich — the labradorite-to-anorthite range — and it is considerably darker than the feldspars of granite. This is the first reason the rock reads dark rather than speckled.

Pyroxene. The pyroxene group — augite and pigeonite in the Chinese material — is close to black in hand specimen. Where true granite carries pale mica, these rocks carry dark pyroxene through the body of the stone.

Iron oxides. Magnetite, titanomagnetite and ilmenite fill the spaces between the crystals. These are opaque, near-black minerals, and they close the gaps in the texture. The more completely they fill the interstices, the more uniform the black is, with fewer light patches showing through.

Shanxi Black gives a numeric picture of a mafic mix: plagioclase at roughly 50%, augite-pigeonite at roughly 35%, andesine at roughly 5%, with hornblende, biotite and titanomagnetite making up the balance. Read that as a purchasing document and the point is this — the stone is dominated by dark minerals, and the small variation between quarry blocks is mostly variation in how much of the iron oxide component is present and how evenly it is distributed.

What to take from this section. The black in black granite is intrinsic and mineral, not a surface treatment. A supplier does not need to explain how the stone got its colour; it is in the rock. What a buyer should verify instead is consistency: whether the black is even across the blocks, and whether the grain size matches the approved sample.

Why Polished Black Granite Reads as a Mirror

The polished surface of a good black stone is one of the most recognisable finishes in the trade, and it is a direct product of texture and grain size rather than of the polishing process alone.

Absolute Black from the Dharwar Craton is the reference case. The rock is fine to medium grained with an ophitic texture — ophitic meaning the plagioclase crystals are enclosed by, and interlock with, the pyroxene. The practical consequence of that texture, in a fine grain, is that there are no visible crystal boundaries at the surface after polishing [source: stonecrestinternational.com]. Light is reflected from a continuous surface rather than being scattered off a patchwork of contrasting crystals, and the result is a uniform, mirror-like black.

Contrast that with a true granite, where the crystals are large, strongly contrasting in colour and visibly interlocked. A polished granite facade reads as a speckled field precisely because every crystal face reflects differently. The dark, mafic rocks can be much finer, and the finer and more tightly interlocking they are, the more the surface reads as a single plane.

Why a buyer should care about texture. Grain and texture are the properties that make one black granite look premium and another look flat and mottled — and they are not visible on a supplier's price list. They are visible on a sample. When you evaluate a black granite, judge the uniformity of the polished face at close range and at an angle, not just the colour in a photograph.

The physical data that travels with this material. For Absolute Black, hardness sits in the 6–7 Mohs range and density is reported at about 2,800–3,000 kg/m³. Water absorption is reported in a range of roughly 0.05–0.30%, and the range itself is the honest figure here — sources differ, quarry by quarry, so ask for the value for your specific supplier rather than relying on a single published number. Shanxi Black is reported at about 7 Mohs with a density of 2.9–3.2 g/cm³; G684 Fuding Black has a published bulk density of 2.86. Note that units are quoted as published: 2,800–3,000 kg/m³ is the same as 2.8–3.0 g/cm³. Density matters directly at the container loading stage, because weight rather than volume is usually what limits a stone shipment.

Black Granite Quarry: Absolute Black and the Dharwar Craton

India's Karnataka state is one of the established sources of very dark, uniform black stone, and the geology behind it explains both the appearance and the commercial structure of the supply.

Absolute Black is quarried in the districts of Chamarajanagar, Hassan, Bangalore Rural, Mysuru and Tumkur, all within the Dharwar Craton — an ancient block of continental crust. The rock is a dolerite (also called diabase or microgabbro), and the key geological fact is that it occurs as ancient intrusive bodies that predate the Deccan volcanic activity. This is not flood basalt; it is older, deeper-seated material that was intruded into the craton long before the Deccan episode.

That origin story is why the material behaves the way it does. As an intrusive rock it cooled slowly enough to develop a fine-to-medium, tightly interlocking texture — the ophitic fabric described above — and that fabric is what gives the polished face its uniform appearance.

The naming warning that matters most in this category. "Absolute Black" has become a category name, not a single-origin product. Material sold under it is produced in India, South Africa, Zimbabwe and China, and quality varies from quarry to quarry. When a customer specifies Absolute Black, they are specifying a look. When you buy it, you are buying a specific quarry's stone that may or may not match what the customer saw elsewhere.

There is a piece of folklore in circulation that Karnataka is the source of all Absolute Black. It is not accurate — other countries produce material under the same name — and it is the kind of claim that comes from a supplier's marketing rather than from geology. Treat claims of exclusivity as sales language, and buy on the sample and the test data.

What to do about it:

Ask for the quarry location — district level at minimum — alongside the trade name, and record it on the PO.
If you are re-ordering, re-order against the quarry, not the name. A different district can deliver a different grain and a different depth of black.
Retain a physical reference sample from every shipment that is going to be repeated, and date and label it.

India, Part Two: Black Galaxy — One Deposit, One Set of Constraints

Black Galaxy is the clearest example in this category of geology dictating commercial reality, and it is worth understanding in detail even if you do not buy it, because it shows how concentrated a "black granite" supply chain can be.

Where it comes from. Andhra Pradesh, Prakasam district, Chimakurthi village, near Ongole. The stone moves to export through the ports of Chennai and Krishnapatnam.

What it is. The geological name is gabbric anorthosite — again, not a true granite. The distinctive gold flecks against the dark ground are iron-bearing enstatite, a pyroxene in the bronzite range; the iron content is what gives the flecks their bronze-gold appearance rather than a pale grey.

It comes from a single deposit. The material is worked from one deposit area of roughly 40 quarry sites across more than 400 acres. This is the structural fact for a buyer: unlike a category name such as Absolute Black, which is sourced from several countries, Black Galaxy's supply is geographically concentrated in one district in one state. Concentration has two sides — consistency is generally high because the material is geologically one body, and supply risk is concentrated because there is no second region to draw from when that district has a problem.

The hardness figure is the one to write down. Black Galaxy has a Mohs hardness of about 4.5. That is well below the 6–7 range of granite, and it is the single most consequential fact about the material for anyone specifying it. A stone at 4.5 is more easily scratched than the other materials in this family, which makes it a finish-sensitive choice for countertops and for high-traffic flooring, and it makes handling and fabrication practice more important. If your client has specified Black Galaxy for a countertop, that is a conversation worth having before the slabs are cut rather than after the first scratch.

The yield figure is the one to write down next. Only 30 to 40% of production reaches large gang-saw size — blocks larger than roughly 2.40 m × 1.20 m × 1.00 m. In other words, a majority of what comes out of the ground cannot be cut into large slabs, and has to go into smaller formats.

What the yield number means in practice:

The price per square metre of large-format Black Galaxy already contains the cost of the material that could not be used at that size.
Availability of large slabs is constrained by the deposit's structure, not by scheduling. A supplier who says large formats will take longer is usually describing geology, not inefficiency.
For a project that needs large, matched panels, Black Galaxy is a demanding specification. For work in small formats — tiles, small components, monuments, decorative inlays — the economics are more favourable, because small formats are what the rest of the block is suited to anyway.
If a quote for large-format Black Galaxy comes in unusually low, ask what size blocks the material is being cut from. The arithmetic of a 30–40% yield does not disappear.

Aliases to expect. The material is also traded as Star Galaxy, Galaxy granite and Ongole Galaxy. As with all trade names in this family, the alias tells you the look, not the quarry.

China's Black Stone Industry: The Names an Importer Meets

China is where a large part of the container-volume black stone trade is supplied from, and the Chinese black family is broad. Four names cover most of what an importer will encounter:

Shanxi Black — Hunyuan, Shanxi. A gabbro-diabase with a Mohs hardness of about 7 and a strong export position.
G684 Fuding Black — Bailin, Fuding, Fujian. A basalt, not a granite, and the subject of the industry story below.
Mongolia Black (蒙古黑) and Fengzhen Black (丰镇黑) — from Inner Mongolia. These belong to the hard granite-type group, and they are the reference point against which G684's lower hardness is measured.
Hebei Black (河北黑), also sold as China Black.

The Chinese materials matter to a buyer for a supply reason as much as a geological one: China's black stone industry has been through a visible cycle of rapid growth, fragmentation, and then consolidation driven by environmental regulation. The G684 story is the clearest case of that cycle, and it is worth knowing because similar dynamics can affect other Chinese quarry districts.

Shanxi Black: Reserves, Grades and the Monument Trade

Hunyuan, Shanxi produces one of the most widely specified Chinese black stones, exported to the United States, Australia, Japan and Korea. The rock type is a gabbro-diabase, fine grained and massive in structure — a combination that takes a deep, even polish.

Composition and properties. Plagioclase at roughly 50%, augite-pigeonite at roughly 35%, andesine at roughly 5%, with hornblende, biotite and titanomagnetite in the balance. Mohs hardness is about 7 — at the top of the range for this family — and density is 2.9–3.2 g/cm³.

Scale. Published figures put the deposit's reserves at approximately 193 million cubic metres, with block output in the order of 35,000 cubic metres per year. Figures of this type come from industry reporting and shift with quarrying activity and with the source you read, so treat them as an indication of scale rather than a fixed capacity, and confirm current availability with your supplier. What the numbers describe is a material with a deep reserve base and a production rate that is disciplined rather than explosive — which is generally a favourable combination for a buyer who needs the same stone next year.

Names to expect. Shanxi Black travels as Taibaiqing (太白青), Dihuang Hei / Emperor Black (帝王黑), and the export name Dynasty Black.

Grading is where this material is won or lost. Shanxi Black is sorted into A and B grades, and separately by crystal size into large, medium and fine crystal classes — the trade's 大花 / 中花 / 细花 division. Medium and fine crystal grades are generally preferred, and the A grade goes largely to the monument and tombstone trade.

That last point has a direct consequence for architectural buyers. When the monument trade takes the top grade, an architectural order may be filled from B grade or from a mix, and the visible difference between crystal classes is real — the large-crystal material reads noticeably more granular than the fine. Do not buy Shanxi Black on "A grade" alone:

State the crystal size class you want in the specification, not just the grade letter.
Ask for the grade definition in observable terms — crystal size, permitted defect count, colour range against a retained sample.
Approve a physical sample in the intended finish, and require the supplier to retain a matching reference piece.
Where the project is colour-sensitive, ask for pre-assembly photographs of the actual pieces before packing.

G684 Fuding Black: A Basalt, a Town, and a Regulatory Reset

G684 Fuding Black is the most instructive material in this category for anyone buying from China, because its history shows how quickly a supply base can be restructured.

Where it is. Fuding, Fujian province — Bailin town, on the north-west slope of Taimu Mountain, at Dazhang Mountain. The quarry area is compact: roughly 0.21 km², about 800 m east-west by 450 m north-south. It sits near Shacheng port, which is a genuine logistics advantage for export.

What it is. A basalt — and it is worth restating plainly, because the name invites the opposite assumption: G684 is a basalt, not a granite. Any supplier describing it geologically as granite is describing it commercially.

Properties. Bulk density is 2.86. Alkali resistance is reported at 99.93–99.96%, which is relevant for a material going into wet or chemically exposed service. Hardness is lower than hard granite-type Chinese blacks such as Shanxi Black and Fengzhen Black — a property to weigh wherever abrasion resistance drives the specification.

The industry history, which is the reason this material has a story at all:

Period	What happened
1992	Mine established at Bailin
1998	Large-scale extraction begins
Growth phase	Fuding Black comes to account for 80% of China's black stone market; at its height the district runs 348 workshops
2018	Environmental consolidation: the 348 workshops are reorganised into 28 joint-stock companies plus 2 deep-processing enterprises

How to read that timeline as a buyer. The 348-to-28 restructuring is a template for what regulation can do to a stone district: a fragmented cottage industry is replaced by a much smaller number of corporate entities, working under environmental requirements that cost money to meet. Four practical consequences follow:

Your supplier list for this material is shorter than it was, and the entities are larger. Procurement and compliance are generally simpler; the number of independent sellers you can play off against each other is smaller.
Verify the entity you are contracting with. After a consolidation of this kind, the marketing name, the quarry operator and the exporting company are not necessarily the same organisation. Ask who holds the mining licence and who is actually cutting your order.
Expect compliance cost to sit inside the price. Environmental control is not free, and a price that ignores it is a price that will not survive the next inspection cycle.
Track policy in your producing districts generally. The Fuding case shows that a district's structure can change within a single season, and buyers who treat the supplier landscape as static are the ones caught out.

What it is used for. Interior and exterior decoration, architectural components, countertops, wash basins and tombstone material. Given the hardness comparison above, the countertop application is the one where the material choice deserves a second look against the alternative hard blacks.

Yield: The Number Most Buyers Learn About Too Late

Yield — the share of quarried material that actually becomes sellable slabs — is the quiet driver of black granite pricing, and Black Galaxy's numbers make the mechanism visible.

The published figure for Black Galaxy is that only 30 to 40% of production reaches large gang-saw size, meaning blocks larger than roughly 2.40 m × 1.20 m × 1.00 m. The remainder is real stone; it is simply stone that cannot become a large slab, and it is sold into smaller formats instead.

Why this belongs in a purchasing conversation:

Price already reflects yield. When yield is low, the cost per square metre of large-format material carries the cost of the material that could not be used at that size. A low quote for large formats is a question, not a bargain.
Large-format availability is a geological constraint, not a logistics one. No amount of scheduling pressure increases the share of the deposit that comes out as big blocks.
Format strategy can be optimised. If your project can use small formats — tiles, components, monuments, banding — you are buying into the part of the production that is abundant, and the economics generally improve.
Yield varies by material, and you should ask. Black Galaxy's 30–40% is a documented case. It does not describe Shanxi Black, Absolute Black or G684, and you should not assume it does. Ask each supplier, for each material, what proportion of production reaches the large sizes you are specifying, and what the maximum panel size is that they can consistently deliver.

A supplier who can answer the yield question with a number and a maximum panel size is a supplier who understands their own quarry. That answer is worth more than a page of marketing copy.

What Geology Means for Your Purchase Order

The geology in this article converts into a small number of concrete purchasing decisions. Here is the chain, from rock to paperwork.

Hardness determines application suitability. The family spans roughly 4.5 to 7 on the Mohs scale. Black Galaxy at about 4.5 is more easily scratched; Shanxi Black at about 7 is among the hardest in the group; G684 is lower than the hard granite-type Chinese blacks. For countertops and high-traffic flooring, this single figure can decide whether a specification is sensible.

Density determines freight arithmetic. Reported values across the family run from 2.86 (G684) through 2.9–3.2 g/cm³ (Shanxi Black) to about 2,800–3,000 kg/m³ (Absolute Black). Weight, not volume, is usually the binding constraint on a stone container, so these are the numbers your loading plan is built on.

Water absorption determines sealing and exposure strategy. For Absolute Black the reported range is roughly 0.05–0.30%, and the spread between sources is the point — ask for the value for the material you are actually buying rather than relying on a category figure.

Texture and grain determine appearance consistency. The ophitic, fine-to-medium texture of Absolute Black is what produces the uniform mirror face. Shanxi Black's crystal size classes exist because the monument trade discriminates between them. Both are visible on a sample and invisible on a price list.

Origin structure determines supply risk. Black Galaxy comes from a single deposit. Absolute Black is a category name produced in several countries. G684 comes from a quarry area of about 0.21 km² operated by a consolidated group of 28 companies. Each structure implies a different risk profile and a different re-ordering discipline.

The one-line translation: buy the rock and the quarry, not the name. The name is a starting point for a conversation, not a specification.

How to Ask: A Question Set for Black Granite Suppliers

Most disappointing black granite purchases trace back to a question that was not asked at the quotation stage. This is the set that covers the geology-derived risks:

Question	Why it matters
What is the rock type — basalt, dolerite, gabbro, anorthosite?	It fixes the property range; "granite" does not
Which quarry and which district?	Trade names are not quarry-specific, especially category names
What are the hardness, density and water absorption values, and to which test standard?	Values without a stated standard are not comparable
What proportion of production reaches the large sizes I am specifying, and what is your maximum panel size?	Yield drives price and availability
For Shanxi Black: which crystal size class, large, medium or fine?	Grade letters alone do not control appearance
For Black Galaxy: the intended application, given a hardness of about 4.5?	Scratch resistance is the material's limiting property
For G684: which legal entity holds the mining licence and cuts the order?	Post-consolidation, the operator and the seller may differ
Can you supply a physical sample in the finish I am buying, and retain a matching reference piece?	The sample, not the name, is the specification
Which port does the material ship from?	Fuding sits near Shacheng port; Black Galaxy moves via Chennai and Krishnapatnam

Supply Stability: Reading a Quarry's Structure

Supply stability in this family is largely a function of how the material occurs in the ground, and the four reference materials illustrate four different structures.

Single-deposit supply (Black Galaxy). One deposit, roughly 40 quarry sites. Consistency between shipments is generally good because the material is one geological body; resilience is lower because there is no alternative district. If you build a programme on Black Galaxy, qualify more than one operator within the district and understand how each is licensed.

Multi-origin category supply (Absolute Black). Material produced in India, South Africa, Zimbabwe and China under one name. Supply is more resilient, but the burden of consistency moves to you: a re-order placed against the name may arrive from a different origin and a different quarry. Re-order against the quarry.

Deep-reserve, disciplined-output supply (Shanxi Black). Published reserve figures in the order of 193 million m³ and block output in the order of 35,000 m³ per year describe a large deposit worked at a measured rate. For a buyer, the practical questions are grade availability — the monument trade takes the top grade — and crystal size consistency across shipments.

Consolidated district supply (G684 Fuding Black). A compact quarry area of about 0.21 km², an industry restructured from 348 workshops into 28 joint-stock companies plus 2 deep-processing enterprises in 2018, and a location near Shacheng port. Supply is corporatised and compliance-driven; the practical question is which entity you are actually buying from.

Three habits that follow from all four cases:

Qualify two suppliers per material, and know which quarry each draws from. Two names on a list mean little if both are buying from the same pit.
Put the quarry, the rock type and the physical values on the PO, not just the trade name.
Keep a dated physical reference sample from every repeat shipment. It is the document that can settle a colour or grain dispute later, and it costs nothing to keep.

Comparing the Four Reference Blacks

	Shanxi Black	G684 Fuding Black	Absolute Black	Black Galaxy
Origin	Hunyuan, Shanxi, China	Bailin, Fuding, Fujian, China	Karnataka, India (Dharwar Craton)	Chimakurthi, Prakasam, Andhra Pradesh, India
Rock type	Gabbro-diabase	Basalt	Dolerite / diabase / microgabbro	Gabbric anorthosite
Mohs hardness	About 7	Lower than Shanxi Black and Fengzhen Black	6–7	About 4.5
Density	2.9–3.2 g/cm³	2.86 (bulk)	About 2,800–3,000 kg/m³	—
Water absorption	—	—	About 0.05–0.30%	—
Distinctive feature	Fine-grained, massive; A/B grade; crystal size classes; monument demand	Alkali resistance 99.93–99.96%; quarry ~0.21 km²; 348 workshops consolidated to 28 companies plus 2 deep-processing enterprises in 2018	Fine-to-medium, ophitic texture; polishes to a uniform mirror face; category name, multi-origin	One deposit, ~40 quarry sites over 400+ acres; gold flecks are iron-bearing enstatite; 30–40% gang-saw yield
Export logistics	Ships to the US, Australia, Japan and Korea	Near Shacheng port	—	Via Chennai and Krishnapatnam

Values are quoted as published, and density units are as they appear in the sources; 2,800–3,000 kg/m³ is equivalent to 2.8–3.0 g/cm³. Treat this table as a framework for questions, not as a substitute for test data on the material you are buying.

FAQ

Where does black granite come from?

There is no single answer, and that is the point. China supplies Shanxi Black from Hunyuan in Shanxi and G684 Fuding Black from Bailin in Fujian. India supplies Absolute Black from the Dharwar Craton districts of Karnataka and Black Galaxy from a single deposit at Chimakurthi in Andhra Pradesh. South Africa, Zimbabwe and Brazil also produce black stone sold under overlapping names. Because the trade names travel further than the geology does, the reliable practice is to record the quarry and district on the purchase order rather than to rely on the name alone.

Is black granite really granite?

Commercially, yes — it is bought and sold as black granite, and ASTM C119 permits these dark igneous rocks to be quarried and sold under that name. Geologically, it is usually something else: dolerite, basalt, gabbro or anorthosite, depending on the material. Neither statement cancels the other. The rock is genuine, natural and dimension-grade; the word "granite" is a trade category rather than a mineralogical claim.

Why is Black Galaxy softer than other black granites?

Black Galaxy is a gabbric anorthosite with a Mohs hardness of about 4.5, well below the 6–7 range of granite, and the difference comes from its mineralogy. For countertops and for flooring in heavy-traffic areas, this means greater susceptibility to scratching, and it is worth confirming the application is suited to the material before the order is placed.

Does the trade name tell me which quarry the stone comes from?

Sometimes, and not reliably. Absolute Black has become a category name produced in India, South Africa, Zimbabwe and China, with quality varying by quarry. Black Galaxy, by contrast, comes from a single deposit at Chimakurthi. The general rule is to record the quarry and district on the purchase order, whatever the trade name says.

Which is harder — Shanxi Black or G684 Fuding Black?

Shanxi Black is the harder of the two, at about 7 on the Mohs scale. G684, a basalt, is reported as lower in hardness than Shanxi Black and other hard granite-type Chinese blacks such as Fengzhen Black.

Can I get large slabs of Black Galaxy?

Large-format availability is limited by the deposit: only 30 to 40% of production reaches gang-saw size, meaning blocks above roughly 2.40 m × 1.20 m × 1.00 m. Large slabs can be supplied, but the format constraint is geological, and the price of large formats reflects the material that could not be used at that size. Ask for the maximum panel size your supplier can consistently deliver.

Why did the supplier landscape for Fuding Black change?

Between 1992, when the mine was established, and 2018, the district grew to 348 workshops and at its height supplied around 80% of China's black stone market. In 2018 an environmental consolidation reorganised those workshops into 28 joint-stock companies plus 2 deep-processing enterprises. If your supplier list for G684 looks different from a few years ago, that is the reason.

Does all Absolute Black come from Karnataka?

No. Material sold under the Absolute Black name is also produced in South Africa, Zimbabwe and China. Claims that one region is the sole source are supplier marketing rather than geology, and they should not shape a sourcing decision.

What should go on the purchase order?

The quarry and district, the rock type, the physical values with their test standards, the finish, the dimensional tolerances, the crystal size class where relevant (Shanxi Black), the accepted reference sample, and the packing and labelling requirements. The trade name can appear as well, but it should not stand alone as the material description on the document.

Summary

Black granite is a commercial category that covers several dark, mafic igneous rocks — dolerite, basalt, gabbro, anorthosite — sold under one trade name that ASTM C119 explicitly permits. The black colour is mineral, coming from calcic plagioclase, pyroxene and iron oxides; the mirror polish comes from a fine, tightly interlocking texture with no visible crystal boundaries; and the properties that decide whether a material suits your project — hardness, density, absorption, yield — vary widely inside the name.

The four reference materials each teach something different. Absolute Black shows that a trade name can outgrow its origin and become a category produced in several countries. Black Galaxy shows how a single deposit shapes everything: a distinctive look, a hardness of about 4.5, and a 30–40% gang-saw yield that puts a floor under the price of large formats. Shanxi Black shows what a deep reserve and a disciplined output rate look like, and why the monument trade's appetite for the top grade changes what architectural buyers receive. G684 Fuding Black shows that a supply base is not permanent — 348 workshops became 28 companies in a single regulatory cycle.

None of this is a reason to avoid the category. It is the reason to buy it the way the material deserves: by rock type and quarry, against test values with stated standards, against a retained physical sample, with the yield and maximum panel size confirmed in writing before the container is booked. The name on the invoice describes what the stone looks like. Everything that decides whether the order goes well is underneath it.