[Rockhounds] ID help

[pmodreski at aol.com]

Interesting photos and mineral puzzle, and I like the suggestions that have been made.? Titanite (sphene) and orthoclase (adularia) both?could be?possibilities.? I just looked at pictures on Mindat of amblygonite (montebrasite)--that does very much look like your mineral too.? Yes, it does resemble topaz, but maybe "not quite"; at least not the typical habit of topaz.

If the hardness is really >6, and not just "6", that should rule out amblygonite and orthoclase and titanite as well; I know that accurate hardness tests can be quite tricky, especially for the harder minerals.

One of your pieces looks to be free of matrix; this is a case where an accurate specific gravity test would help to narrow the possibilities, if you had the equipment to do it.? It's?often easy to suggest "definitive" tests, but which the person with the specimen doesn't necessarily have the ability to make.? Of course, determining the approximate refractive indices on a fragment would be a "best way" to identify the mineral, but that's the same problem of having the equipment to do so.

Some parameters for those candidate minerals:

orthoclase????????sp.gr. 2.57?????????hardness 6
amblygonite???? sp.gr. 3.04-3.22? hardness 5.5 - 6
titanite?????????????sp. gr. 3.40-3.55? hardness 5 - 5.5
topaz?????????????? sp. gr. 3.4-3.6?????hardness 8

Good luck!
Pete

-----Original Message-----
From: Pete Richards <rpr at heidelberg.edu>
To: Rockhounds at drizzle.com: A mailing list for rock and gem collectors <rockhounds at lists.drizzle.com>
Sent: Wed, Jun 24, 2009 7:36 am
Subject: Re: [Rockhounds] ID help


I'll try a different suggestion. Could it be titanite? Alpine titanite is often green, sometimes light. Some of the angles look right, and I imagine I see a groove in one view that might be a re-entrant region caused by the common contact twinning. I don't know anything about fluorescence....?
?
Pete Richards?
?
On Jun 23, 2009, at 12:50 PM, Lawrence Rush wrote:?
?
> I just got a box of minerals from Pakistan which contained 2 pieces > of an unidentified material. These are unfamiliar to me, and I need > some help.?
>?
> The color is a sea green, translucent. The crystals are well > formed, appear to be perhaps Tetragonal or Orthorhombic. They have > 4 distinct sides, diamond-shaped in cross section, with sharp low > angle edges on 2 sides. The hardness is greater than 6. The matrix > is quartz, evidently a pegmatite mineral. No locality, but all of > the others from this supplier were from Afghanistan, Pakistan, and > Waziristan.?
>?
> I suspect they are Topaz, but the shape and color have me > questioning this.?
>?
> I posted photos on http://www.connroxminerals.com/temp.html?
>?
> Any thoughts??
>?
> Thanks...Larry?
>?
>?





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