Formula: Pb(Cu,Zn)2(AsO4)2.2H2O
Origin of name: for W. Thometzek, mine director at Tsumeb, Namibia
Crystal system: monoclinic or triclinic
Crystal class: 2/m or 1
Twinning:
Unit cell: a = 9.077, b = 6.300, c = 7.661, β = 116.99°
Colour: Bluish green to green, greenish yellow
Diaphaneity: Semitransparent
Luster: Earthy
Habit: Crystals tabular 1 micron by 20 micron long in aggregates, platy to wedge-shaped crystals, in crusts
Hardness: 4.5
Specific gravity: 5.21
Cleavage:
Tenacity:
Streak: White
Synonyms/varieties:
Comments: related to helmutwinklerite and tsumcorite
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