FMF - Friends of Minerals Forum, discussion and message board

[Jordi Fabre]

[Woody Thompson]

Hi Jordi,

Thanks for rescuing my posting above. I wondered why it didn't appear, but maybe had a typo error in "houses" or whatever it was that provoked the automatic spam response?

Regarding the necessity of sealing granite countertops, maybe there are less solid granites in some quarries, that are not fresh and solid and may have a little porosity or weakened grain boundaries. Even here in glaciated New England, the Conway Granite (famous for its crystal-bearing miarolitic cavities) is so crumbly in places that you can excavate it with a shovel.

Cheers,
Woody Thompson

[Jesse Fisher]

The study and classification of rocks (known as "petrology") is a branch of the geological sciences that employes a complex and and often www.spam.org terminology, perhaps rivaled in the other sciences by molecular biology. I don't think one can expect a manufacturer or salesman dealing in dimension stone to know the difference between a granodiorite, a quartz monzonite, a gabbro or an anorthosite, so they all just get the generic name "granite" regardless of whether the rock is a true granite or not. I don't expect that many even know the difference between an igneous and a metamorphic rock, so all manner of schists get labeled "granite" as well.

I suspect that the number of geologists with any petrological training is very very small within the population of potential customers for these things, so I seriously doubt that the average buyer of stone counter tops knows or cares about the differences either. I'm sure all they want is something durable and pretty.

Being a member of that "very very small" group, I sometimes enjoy going through the sales samples at tile and counter top dealers, looking for interesting rock types and, I'm sure, boring any poor salesman that happens by with the details. I once recall finding a stone that was a quartz-mica schist with thousands of little red garnet grains in it. About the time I got to speculating on what these must have done to the sawing and polishing equipment, I think the salesman heard his mother calling!

[Jordi Fabre]

[John Medici]

Just a note on a recent stone countertop my family purchased. All salespeople we talked to called everything in the establishment "granite". The one we chose was definitely not granite or marble. It was mainly black swirls with some swirls and splotches of red (a combination of hematite and magnetite) with irregular veins of white quartz interspersed in it. On questioning a supervisor or two while trying to avoid being a pest, I came to the conclusion that it may have come from an iron mine (or stone slab mine) in Brazil. This may or may not be the case, but we have enjoyed having it, and one can take a magnet to it to find the zones of magnetite.

[rantoniobz]

[GneissWare]

I think I NEED that banded iron somewhere in my next house. The pillow basalts are neat too.

[Jean Sendero]

Love the pillowed basalts. Just text book and it is like mapping an outcrop in the Abitibi.

I have followed this treat on and off and now have a simple word of advice in regards to what not to say and I place the emphasis on "what NOT to say" to freinds of yours that are neophyte in petrology and think that their brand new granite counter top is granite. I have learned by experience (twice) to never, never say to a proud new owner of a granite countertop that actually it is not granite but a gneiss or a labradorite or else.....they get very upset with you and blame you for the ignorance of the seller.

Cheers

J

[GneissWare]

I just tell them "your granite counter is very gneiss"

[trtlman]

That banded countertop is awesome. Would that be the same thing as banded agate? That's why I like is to much, it reminds me of agate