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Identity Helpminerals on Amethyst cluster

13th Aug 2015 04:49 UTCSophiaJoy MB

I'm wondering what the minerals on the Amethyst cluster are. The mineral has black/brown inclusions (sphere?), and doesn't look like Amethyst because the color is not purple, and the shapes look different from the Amethyst around it. I did a hardness test and it seems like it's around 7 but I can't say for sure because the mineral is so small.

Would you tell me what it is and the inclusions are?

Thanks!

(I've learned a lot on Mindat. Thank you very much!)

13th Aug 2015 08:24 UTCRock Currier Expert

It looks like little burs of white quartz growing on the amethyst. If the little white burs have little black/brown/possibly golden needles associate with them they are likely to be goethite.

13th Aug 2015 08:37 UTCSophiaJoy MB

Thank you, Rock Currier.

I don't see needles. I can't say for sure, though, because they are soooo small even with a loupe. :-(

13th Aug 2015 10:08 UTCUwe Ludwig

Amethyst is very often accompanied with an iron mineral. If there are needles than Goethite is very probable. The quartz crystalls are the second generation of this quartz vein. Also not out of the common.

Rgds.

Uwe Ludwig

13th Aug 2015 10:32 UTCJohan Kjellman Expert

as a general statement - goethite needles can be oriented spherically

cheers

13th Aug 2015 11:55 UTCSophiaJoy MB

-- moved topic --

15th Aug 2015 04:17 UTCSophiaJoy MB

I didn't know Goethite can be spherical. :-)

You guys rock! Thanks!

17th Aug 2015 08:39 UTCGregg Little 🌟

Sophia;

The little light brown crystals could be a carbonate, calcite, dolomite and siderite being the common candidates as a late stage, low grade hydrothermal mineral.(the latter two if iron is floating around in the system) They are very small in the photos but do look like they have crystal terminations.

17th Aug 2015 09:30 UTCsteven garza

Dear Gregg;

That is a piece of Brazilian amethyst, which occurs in geodes, not a vein; the only carbonate they have are calcite, VERY late stage, &, it's always white to pale yellow. The terminations you see are quartz terminations (don't magnify the pics by clicking on them - they only go so far; I just increase the zoom on my screen to about 300, to see things better. A little loss of resolution, but, still get better results.) ; the calcite came in LONG after ALL the quartz cycles were finished.

19th Aug 2015 07:04 UTCGregg Little 🌟

Hydrothermal is the term for how the minerals are deposited. Geodes and veins are descriptions of the geometry, and probable genesis, of the space that the crystallization occurs in. Calcite crystallization after all the quartz cycles have finished is still hydrothermal deposition. Hydrothermal deposition can occur in geodes, veins, fractures, faults, bedding planes, leached zones, etc.

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