Lehmannite

lehmannite

Images

Formula: Na₁₈Cu₁₂TiO₈(AsO₄)₈FCl₅
Arsenate, titanium-bearing mineral, epitaxial on arsmirandite
Crystal System: Monoclinic
Specific gravity: 3.676 calculated
Hardness: 4½
Streak: Greyish green with an olive hue
Colour: Dark greyish green to olive-greenish black
Environments

Fumeroles

Lehmannite is a relatively new mineral, approved in 2018 and to date (November 2023) reported only from the type locality.

Localities

At the type locality, the Arsenatnaya fumarole, Second scoria cone, Northern Breakthrough, Great Fissure eruption, Tolbachik Volcanic field, Milkovsky District, Kamchatka Krai, Russia, lehmannite occurs as equant crystals, up to 20 × 20 × 30 μm³, usually intergrown to form thin crusts, up to 2 × 3 cm² in area. Associated minerals include arsmirandite, hematite, sanidine, sylvite, halite, tenorite, cassiterite and rutile (HOM, Mindat).

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