Crystal Mimetite

Chemical Formula

Pb₅(AsO₄)₃Cl

Composition

Lead chloro-arsenate. The arsenate radical (AsO₄) may be partially replaced by a phosphate radical (PO₄) or vanadate radical (VO₄), and thereby forms a series with Pyromorphite and Vanadinite.

Variable Formula

Pb₅([As,P,V]O₄)₃Cl
 

Color

Light yellow, lemon-yellow, dark yellow, orange, brown, reddish-brown, and yellow-green. Rarely colorless or white. May also be multicolored orange, yellow, and greenish-yellow.

Streak

White

Hardness

3.5 - 4

Crystal System

Hexagonal

Crystal Forms 
and Aggregates

Occurs in small, slender, prismatic crystals and in mammilary and botryoidal crusts. A rare habit is large, stubby, hexagonal crystals. Also occurs as wedge-shaped crystals, acicular, radiating, reniform, encrusting, and in curvy and fibrous aggregates. Some larger crystals may be hollowed out on the ends or have a hopper growth pattern.

Transparency

Transparent to translucent

Specific Gravity

7.0 - 7.3

Luster

Resinous to adamantine

Cleavage

Indiscernible

Fracture

Subconchoidal to uneven

Tenacity

Brittle

Complex Tests

1) Dissolves in hydrochloric acid
2) Gives off a strong garlic odor if heated (fumes are poisonous!)

In Group

Phosphates; Arsenates

Striking Features

Color, crystal habits, mineral associates, and mode of occurrence.

Environment

As a secondary mineral in the oxidation zone of lead ore deposits.

Rock Type

Sedimentary, Metamorphic

Popularity (1-4)

2

Prevalence (1-3)

3

Demand (1-3)

1