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Identity HelpAmethyst / Smokey Quartz ‘spear’ from where?

19th Dec 2017 22:20 UTCDennis McCoy

05127390017057052302738.jpg
Anyone have an idea where this may be from? Purchased without label from an estate.

How would you describe this growth form? It is amethyst, then Smokey Quartz with a rind of milky white quartz.

01312870017057052326859.jpg

05585480015653038158585.jpg

20th Dec 2017 17:42 UTCTheodore Hansen Theo

This is actually called "tessin" crystal shape of quartz

21st Dec 2017 01:11 UTCDennis McCoy

Thanks Theo.

21st Dec 2017 09:12 UTCErik Vercammen Expert

This crystal has grown in 2 times. The first phase was rather clear quartz, with iron at the start, that made the formation of ametyst by the radiation of the surrounding rock possible; the outer core of the first phase is 'just' smoky as there was no more iron to cause the ourple color. The second phase was milky quartz, perhaps a quick growth with a lot of inclusions from the forming solution.

23rd Dec 2017 04:31 UTCDennis McCoy

00579160016029340007289.jpg
Here are some micro shots of inclusions and accompanying minerals. There are white sprays (millerite?) and green sprays (malachite?) Any ideas as to what they are and does it help with a location?

02573670015653038161884.jpg



And hematite?
09397490015653038169875.jpg

24th Dec 2017 13:54 UTCEd Clopton 🌟 Expert

Millerite would be pale brassy metallic rather than white, although sometimes it tarnishes green.

26th Dec 2017 04:06 UTCAdam Kelly

I have seen somewhat similar pieces from La Sal, Utah. I happen to have one in my collection.

They find copper minerals nearby so it's a possibility as for as that goes.

That said there are thousands of amethyst localities known, and I'm sure at least that many again unknown.

AK


P.S. I don't think that is a true Tessin Habit Piece. Closer to "Cathedral Quartz"
 
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