Ecdemite

Formula:   Pb₆As₂O₇Cl₄

Origin of name:   From Greek for unusual

Crystal system:   Tetragonal

Crystal class:   Unknown

Twinning:

Unit cell: 

Colour:  Yellow to greenish yellow, orange

Diaphaneity:  Translucent

Luster:   Vitreous to greasy

Habit:  Cystals, tabular, small; foliated masses; thin incrustations

Hardness:   2.5 to 3

Specific gravity:   7.14

Cleavage:   1; {001} perfect

Tenacity: 

Streak: 

Synonyms/varieties:

Comments:   Sometimes spelled ekdemite