Absolute Black Granite

• ABSOLUTE BLACK GRANITE TO THE FUTURE!!! OR SHOULD THAT BE BASALT?

This is not meant to be the definitive guide to absolute black granites, merely an independent and factual assistance to ensure you make the correct specifying or purchasing decision, it may also dispel some of the myths and marketing hype surrounding this material name.

Why? Black is popular, black looks great, black is more expensive, Absolute Black granite has almost become the de facto standard for kitchen tops in some countries, therefore there will always be someone trying to make a quick buck at your expense by selling you an inferior material at the top notch price.

Petrographically, not all black granites are granites, some are basalt, however for generic commercial purposes they are all grouped under the granite name.

Basalts are dark colored, fine-grained extrusive rock. The mineral grains are so fine that they are impossible to distinguish with the naked eye or even a magnifying glass. They are the most widespread of all the igneous rocks. Most basalts are volcanic in origin and were formed by the rapid cooling and hardening of the lava flows. Some basalts are intrusive having cooled inside the Earth's interior.

Terminology

What is meant by "black granite"? To quote from the discussion in ASTM C*****5b Standard we learn the following:

"Black Granites: dark-coloured igneous rocks defined by geologists as basalt, diabase, gabbro, diorite and anorthosite are quarried as building stone, building facings, monuments, and speciality purposes and sold as black granite. The chemical and mineralogical compositions of such rocks are quite different from those of true granites, but black granites nevertheless may be satisfactorily used for some of the same purposes as commercial granite. They possess an interlocking crystalline texture but, unlike granites, they contain little or no quartz or alkali feldspar. Instead, black granites are composed dominantly of intermediate to calcic plagioclase accompanied by one or more common dark rock-forming minerals such as pyroxenes, hornblende, and biotite. Such rocks, because of their relatively high content of iron and magnesium, are designated as ferromagnesian or mafic. An exception is anorthosite which, though commonly dark, consists mostly or entirely of calcic plagioclase". So far a statement by consensus. We can now go ahead to use Black Granite as an umbrella term while offering the material under the (geologically correct) names above.

A more in-depth and technical article written by Asher Shadmon (United Nations' International Commission on Building Stones) may be read here.

To learn more about general rock composition and mineralogy please click here.

Colour

The first common misunderstanding is that of all Absolute Black granites being the same material. They are not and they can vary widely in colour, quality and price!

The original Absolute Black, also known as Sutareboda, is the name for a Swedish black granite which has been quarried for many years.

Probably the most famous Swedish black granite is Ebony Black. It is very hard and durable, takes a beautiful polish and has an almost metallic "ringing" tone when struck with a hammer and chisel. It is also very expensive.

Depending from which quarry it originates it is known as Hallandia AKF No 1, AKF No *5, EGC Black Fined Granied, EGC Black and SS1. We would like to list these correctly therefore please advise if you do know the full details but we do know of the following diabase quarries BRÄNNHULT, DUVHULT, GYLSBODA and HÄGGHULT.

In ***2 Belfast Black granite from South Africa was first exported and shortly afterwards the trade in Italy started calling this granite Nero Assoluto, the literal translation being Black Absolute.

Alternative names have been South African Ebony, South African Black and Prairie. Some of the Southern African granites can actually have a "rice-grained" effect similar to the Canadian Cambrian Black, and the less black qualities also a silver star reflector.

Since the ***0's, Nero Assoluto has become the generic name for many black granites supplied from Italy including Angola, China, India, South Africa, Zimbabwe and many other countries, therefore unless one is specific the granite could actually be from anywhere!