FMF - Friends of Minerals Forum, discussion and message board

[trtlman]

I have seen many types of countertops that are called granite. Most of them are a mix of black minerals. When I think of granite I think of the classic black and white granite which are the most common granite countertops I have seen. I was wondering are there different types of granite other than the classic black and white granite?

[rockman]

No...Granite does not come in black naturally.
It may be black carrara marble from China.

[Mark Ost]

Granite is a bit of a broad term for a range of intrusive rocks. Some are black and white as you say but some can be quite red if enough Orthoclase feldspars are in the make up. Colorado has very red granites. If they have sufficient biotite content then they may be darker.

[Steve Maslansky]

A good reference to see the myriad of materials used is "The Sourcebook of Decorative Stone" by Monica Price. Firefly Books. Should find it on Amazon.

[GneissWare]

If the specific question is "Are Granite Countertops Always Made of Granite?"
Yes, by definition.

If the question is "Are stone Countertops Always Made of Granite?"
No. They are made of marble, granite, gneiss, conglomerate, and basically anything that has some structural integrity (either naturally or induced by stabilizers).

[trtlman]

Thanks everyone, this is something I been curious about for a while now. Every time I watch one of the home improvement shows they would use granite countertops.

[Mark Ost]

Yep
Just don't take counter tops for granite!

[Bob Hartzell]

Granite is the trade name for any dimension stone composed of minerals that are mostly harder than glass. Marble is the trade name for dimension stone composed of minerals softer than glass (that is why your mother told you not to put your glass down on her marble-top table). Most "granite" is not granite. Much "marble" is not marble, e.g. the famous, brown Tennessee Marble is limestone.

[Bob Hartzell]

Granite is the trade name for any dimension stone composed of minerals that are mostly harder than glass. Marble is the trade name for dimension stone composed of minerals softer than glass (that is why your mother told you not to put your glass down on her marble-top table). Most "granite" is not granite. Much "marble" is not marble, e.g. the famous, brown Tennessee Marble is limestone.

[Roger Warin]

In Belgium, "petit granit" is a limestone rock, blue color black, with fossils, many crinoids.
When the rock is broken, it exudes a smell of sulfur.

Belgian blue limestone
Also known as / varieties
Blue stone, Petit granit - Pierre bleue de Belgique®.
Extraction zone
Basins of Soignies, Ourthe-Amblève and Bocq, provinces of Hainaut, Liège and Namur.
Mineralogical composition
Calcite ± 96 %, traces of dolomite, quartz and pyrite.
Maximum dimensions of rough blocks
Length 4,5 m; width 2,5 m; thickness 2,5 m.

Roger.

[newryqs]

Just to add to the discussion. "Black granite" is a trade term for a wide variety of nearly black coarsely crystalline rock used for ornamental purposes: facings, counter tops, etc..

Best Wishes, Van

[Josele]

Just to comment that right now in Spain and many other countries most countertops instaled in new houses are made with Silestone, a compound with 95% of quartz grains agglomerated with resin. It is available in many colors and textures, some of them very granite-like.

...although I still prefer the white marble

[prcantos]

To illustrate the wide use of the term 'granite' to call some useful rocks, you can visit this thread in the Spanish-side FMF, which contains both technical and trade names:

Brazilian ornamental rocks.

(Use the Google-translation function if necessary). Enjoy it!

[John S. White]

Countertop dealers are really lazy and they simply do not care to deal with the intricacies of the stone world so they recognize very few types of stone, usually only granite, marble, serpentine and slate, no matter what the materials actually are. Black granite may actually be labradorite. Much that is sold as granite is actually gneiss and as stated above much marble is really limestone. If the rock has a wavy pattern throughout it is probably gneiss, which is a very adequate substitute for granite as it is compositionally very similar to granite.

Another widely used misrepresentation is that granite countertops need sealants, that is an expensive chemical that is supposed to keep it from staining. Real granite does not stain and does not require sealing.

[Mark Ost]

All you geologists and chemists should have been interior decorators from the looks of things!