Formula: (Mn,Ca) REE AlMn3+Mn2+(SiO4)(Si2 O7)O(OH) (REE = La, Ce, Nd)
Origin of name: After locality; Andros Island, Cyclades, Greece
Crystal system: Monoclinic
Crystal class: 2/m
Unit cell: a = 8.896 Å, b = 5.706Å, c = 10.083Å, b = 113.88°
Colour: Brown-red
Diaphaneity: Transparent
Habit: As grains of subhedral to euhedral crystals 20 to 60 micrometers, rare up to 200 micrometers across
Specific gravity: 4.03
Synonyms/varieties:
Comments: Forms a series with piemontite.
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