Dalyite

Formula:  K₂ZrSi₆O₁₅

Origin of name:  For Reginald Daly, American geologist

Crystal system:  Triclinic

Crystal class: -1

Twinning:

Unit cell: a = 7.5, b = 7.73, c = 7, α = 106°, β = 113.5°, γ = 99.5°

Colour:  Colourless

Diaphaneity:  Transparent

Luster:  Vitreous

Habit:  Crystals short prismatic

Hardness:  7.5

Specific gravity:  2.84

Cleavage:  3; {101} and {010} good; {100} less distinct

Tenacity: Brittle

Streak: White

Synonyms/varieties:

Comments: