Tacharanite

tacharanite

tobermorite

xonotlite

gyrolite

Images

Formula: Ca₁₂Al₂Si₁₈O₃₃(OH)₃₆
Phyllosilicate (sheet silicate)
Crystal System: Monoclinic
Specific gravity: 2.33 to 2.36 measured, 2.28 calculated
Hardness: 5
Streak: White
Colour: White
Common impurities: Fe,Mg,Na,K
Environments

Volcanic igneous environments
Hydrothermal environments

Tacharanite is a low-temperature mineral, forming at less than 250^oC (Dana).

Localities

At the Bramburg quarry, Adelebsen, Göttingen District, Lower Saxony, Germany, tacharanite occurs in amygdules and fractures in metabasalts and basaltic breccias, and in hydrothermally altered quartzite inclusions in basalt (HOM).

At the Binbill quarry, Cairnie, Huntly, Aberdeenshire, Scotland, UK, tacharanite ia associated with scawtite (HOM).

At the type locality, Portree, Trotternish, Isle of Skye, Eilean á Chèo, Highland, Scotland, UK, the vesicles of a small olivine-dolerite outcrop contained zeolites and some hydrated calcium silicates. The minerals include tobermorite, xonotlite, gyrolite, mesolite, thomsonite, calcite, saponite and tacharanite. The tacharanite occurs as dense, white, cryptocrystalline material (MM 32.745-753, AM 47.173).

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