Apachite

Formula:  Cu₉Si₁₀O₂₉^.11H₂O

Origin of name:  For Apache Indians who live in the locality, Arizona, USA

Crystal system:  Monoclinic, probable

Crystal class:  Unknown

Twinning:

Unit cell: a = 12.89 Å, b = 6.055 Å, c = 19.11 Å, b = 90.42°

Colour:  Blue (Faïence)

Diaphaneity: Transparent to translucent

Luster:  Non-metallic, silky

Habit:  Spherules of radial fibers

Hardness:  2

Specific gravity:  2.80

Cleavage:  None

Tenacity:

Streak: Light blue

Synonyms/varieties:

Comments: A retrograde metamorphic or mesogene mineral, formed at the expense of a prograde calc-silicate and sulphide assemblage in tactites; typically in fractures or crackled zones cutting garnet-diopside rock, replacing both these silicates and calcite