More Hidden Collection

Mineral Matters #443

The more you look, the more you find! So the saying goes.

And you know that I love adding to my Hidden Collection.

This specimen is a case in point. It is labelled simply as charoite, a rare mineral with a complex formula of (K,Sr,Ba,Mn)_15-16(Ca,Na)₃₂[Si₇₀(O,OH)₁₈₀](OH,F)₄·nH₂O, found in alkaline intrusions in Russia, and a valuable semi-precious gemstone. This specimen is polished on one side showing the typical purple (if not a little paler than some) fibrous matted charoite.

Look closely and you can see prismatic dark green crystals of aegirine. Add that to the label.

Then look under various wavelengths of ultraviolet light.

Longwave:

• No reaction.

Shortwave:

• There are small grey areas under white light that are deep red under shortwave. Unknown.

• There is a bright green response in small patches. This is apparently steacyite. Add that to the label.

Mediumwave:

• Steacyite still shows as bright green patches.

• There are tiny specks of a fluorescent blue under mediumwave. Unknown.

Interesting stuff!

I have a few other pieces of charoite somewhere. I must check them out too as they could also host other species.

Below: Charoite, Aegirine, Steacyite, Murunskii Massif, Chara and Tokko Rivers Confluence, Aldan Shield, Russia (Type Locality). Width of 9mm. Click on the image for a closer view.