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PhotosTremolite or diopside Franklin Quarry

10th Jan 2012 17:25 UTCModris Baum 🌟 Expert

This is a "talk page" thread. Click on the topic header at the top of the page to see the photo.

OK. I admit it. After neary 40 years of collecting I still can't tell amphiboles from pyroxenes. (But at least I don't sleep with a teddy bear.)

So it should be easy for the rest of you - right?

Shape wise, this looks like a lot of the tremolite from this quarry. But the latter is mostly dark silvery/gray, rather dull and opaque, and fluoresces very bright pale blue. But that's not always the case.

As for diopside - I never "knowingly" found any here. But it's supposedly common and can have a similar UV response (blue or yellow).

This particular xl fluoresces a moderate greenish yellow.

In any case, it's the only example I ever found that looks like this.

10th Jan 2012 21:25 UTCChester S. Lemanski, Jr.

Modris,

A rule of thumb lies in the fluorescence. The bright baby blue fluorescent material is almost always diopside. The greenish yellow or greenish blue fluorescent stuff is usually tremolite. Since there are pseudomorphs of tremolite after diopside, the crystal morphology is not an accurate guide in many cases.

Chet

10th Jan 2012 21:34 UTCSteven Kuitems Expert

Modris, looks like the typical tremolite and you described its fluorescence correctly. Some of these crystals can be lighter colored or almost white and some can look almost black when there is heavy graphite inclusions in the tremolite.

Steve.

10th Jan 2012 23:20 UTCModris Baum 🌟 Expert

Thanks Chet and Steve - I was hoping you would take the "bait".

I think I get it now - at least for Farber. But I still can't tell amphiboles from pyroxenes :-(

Modris

10th Jan 2012 23:24 UTCModris Baum 🌟 Expert

BTW Steve,

Now I know why so much of the tremolite at Farber looks silvery gray! I guess it should have been obvious.

But why is it that this sort of tremolite is the kind that has the most intense pale blue SW response? I mean really, really bright.

Don't tell me it's really still diopside - with graphite inclusions. Or better - do tell me if that's the case!

Thanks - Modris

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