Polylithionite, Boromuscovite, and Borocookeite

Contributed by: FMS Admin
Date: Nov 13th, 2025
Locality: Sosedka pegmatite vein, Malkhan pegmatite field, Krasnyi Chikoy, Krasnochikoysky District, Zabaykalsky Krai, Russia (See on Mindat)

Description:
Three unfrequent minerals from the Sosedka pegmatite, Malkhan, Zabaykalsky, Russia. Malkhan is known for its beautiful red tourmalines. But it is also produces polylithionite. It is accompanied by a powdery mass of boromuscovite and borocookeite. Boron replaces here the aluminium in the silicate lattice. UV-C @275 nm

Originally posted by groensteenfreterke on Nature’s Rainbow.

Fluorescence under shortwave UV light.

Normal light.

Summary of luminescence responses:

Borocookeite (Mindat) (RRUFF)

• Fluorescence under 275nm LED UV light: White

• Fluorescence under 275nm LED UV light: White