Englishite

Formula:   K₃Na₂Ca₁₀Al₁₅(PO₄)₂₁(OH)₇ ^. 26H₂O

Origin of name:   For G. English, American collector

Crystal system:   Monoclinic

Crystal class:   m or 2/m

Twinning:

Unit cell: a = 38.43 Ǻ, b = 11.86 Ǻ, c = 20.67 Ǻ, β = 111.3°

Colour:  Colourless, white

Diaphaneity:

Luster:   Vitreous to pearly

Habit:   Curved and composite plates in aggregates and layers

Hardness:   ~ 3

Specific gravity:  2.68

Cleavage:   1; {001} perfect, micaceous

Tenacity: 

Streak: 

Synonyms/varieties:

Comments: