This specimen weighs 15.12 grams. It measures 42 mm x 27 mm x 22 mm.

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Hi there! I'm selling this really interesting tincalconite mineral specimen which is covered in hanksite crystals! It is from Searles Lake, near Trona, California, USA. If you have any questions, do not hesitate to ask me.

Tincalconite

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From Wikipedia, the free encyclopedia
Tincalconite

General
Category Nesoborates
Formula
(repeating unit) Na2[B4O5(OH)4]·3H2O
IMA symbol Tnc[1]
Strunz classification 6.DA.15
Crystal system Trigonal
Crystal class Trapezohedral (32)
H-M symbol: (32)
Space group R32
Tincalconite is a hydrous sodium borate mineral closely related to borax, and is a secondary mineral that forms as a dehydration product of borax. Its formula is Na2B4O7·5H2O or Na2[B4O5(OH)4]·3H2O.

Tincalconite typically occurs as a fine grained white powder. It crystallizes in the hexagonal crystal system and has been found as primary euhedral di-rhombohedral, pseudo-octahedral crystals. It is also found pseudomorphically replacing borax crystals. It has a specific gravity of 1.88 and a Mohs hardness of 2. Refractive index values are nω=1.460 and nε=1.470.

While most tincalconite is created by man through exposing borax to dry air, there are natural occurrences of tincalconite, as in Searles Lake, California where it was first described in 1878. In addition to several California and Nevada locations it is reported from Argentina, Italy, Turkey and Ukraine.

The name comes from "tincal", Sanskrit for borax, and Greek, "konis", meaning powder, for its composition and typical powdery nature.