Wallkilldellite

Formula: Ca₄Mn₆As₄O₁₆(OH)₈.18H₂O

Origin of name: from locality, a dell in the Wallkill River, New Jersey

Crystal system: Hexagonal

Crystal class: 6/m 2/m 2/m

Twinning:

Unit cell: a = 6.506, c = 23.49

Colour: Dark red

Diaphaneity: 

Luster: Vitreous

Habit: Crystals platy, 0.1 mm, flattened radial clusters

Hardness: About 3

Specific gravity: 2.85

Cleavage: 1; {0001} perfect

Tenacity: 

Streak: Light orange

Synonyms/varieties:

Comments: