Formula: CaC2O4.H2O
Origin of name: for William Whewell (1794-1866), English naturalist and scientist, professor of moral philosophy, professor of mineralogy at Cambridge, inventor of the system of crystallographic indexing.
Crystal system: Monoclinic
Crystal class: 2/m
Twinning: common
Unit cell: a = 6.276, b = 14.561, c = 10.012, β = 107.083°
Colour: Colourless, white, yellowish or brownish
Diaphaneity: Transparent to translucent
Luster: Vitreous to pearly
Habit: Crystals equant or short prismatic, tabular, twinning common, massive, coarsely crystalline
Hardness: 2.5-3
Specific gravity: 2.21 to 2.23
Cleavage: 4; {101} good, {001} and {010} distinct, {110} indistinct
Tenacity: Brittle, conchoidal fracture
Streak: White
Synonyms/varieties:
Comments: Fluorescent
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