selenite???

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selenite???

Postby shottheradio » Jul 17, 2007 9:53 pm

http://images.search.yahoo.com/search/i ... 0&ei=UTF-8

Check out this like. At work we are selling this gypsum as selenite. I keep telling them that it is not selenite, it is fibrous gypsum. or satin spar.
I want to know what you think??
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Postby Teresa » Jul 17, 2007 10:33 pm

I don't think it matters. There's a school of thought that the choyancy (shimmer) of satin spar makes it appear moonlike (as in moonlight on the water) and hence the reason non-geos call it selenite. There's also the problem like the onyx thread-- the marketers will call something incorrectly, but if *everybody* does it, it's good marketing. ( cf-- Limestones which are called 'marble' in the cut stone trade. You could argue till you're blue in the face that there is no such thing as Carthage marble (actually Warsaw fm. limestone) and you'd get drowned out as I have.

It's quite possible that the supplier calls it selenite, and it comes with the little labels, and you're not likely to fight city hall on that one. Also, 'satin spar' is also applied to some calcite varieties-- I'd rather gypsum be misidentified as selenite (gypsum) than as satin spar (calcite).

As long as they've got the gypsum thing correct, I'd be happy.
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Postby shottheradio » Jul 18, 2007 8:00 pm

so satin spar is a form of gypsum,... correct??
not calcite?
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Postby Teresa » Jul 18, 2007 9:15 pm

Apparently the satin spar name is used for both gypsum AND calcite. Sort of like the onyx thing. Or marble for limestone and marble (and even other rocks, occasionally).

Heck, I've even seen satin spar used as the name of a kind of house paint which has a slight shimmer.

I'd use the mineral or rock name, not nicknames like satin spar. "Blackjack" can be used to name a kind of zinc sulfide, an oak tree or even a WW I general.

Words are such slippery things.
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Postby Bruce Rogers » Jul 27, 2007 3:37 pm

Listeros,

The American Geological Institute Dictionary of Geolgical Terms defines the term satin spar as:

"A white, tranlucent, fibrous variety of gypsum, characterized by a silky luster."

The AGI dictionay is usually consulted as an arbitrater of correct term defiitions.

Cheers,
Bruce Rogers, Earth scientist on a good day
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Postby Squirrel Girl » Jul 27, 2007 5:53 pm

Teresa wrote: There's a school of thought that the choyancy (shimmer) of satin spar makes it appear moonlike (as in moonlight on the water)
Do you mean 'chatoyancy'?
Barbara Anne am Ende

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