Crystal Turquoise

Chemical Formula

CuAl₆(PO₄)₄(OH)₈ • 4H₂O
 

Composition

Hydrous basic copper aluminum phosphate
 

Color

Turquoise-blue, sky-blue, bluish-green, apple-green

Streak

White

Hardness

5 - 6

Crystal System

Triclinic

Crystal Forms 
and Aggregates

Most often nodular, massive, concretionary, botryoidal, and reniform. May also be in veins, in cauliflower-shaped masses, in rounded balls, as crusts, and in stalactitic form. Turquoise crystals are very rare and limited to a few specific localities, where they are found as tiny drusy crystals within thin crusts and in rosette forms.
 

Transparency

Opaque. May be translucent in thin sections.

Specific Gravity

2.6 - 2.8

Luster

Waxy, dull

Cleavage

None

Fracture

Conchoidal

Tenacity

Brittle

In Group

Phosphates

Striking Features

Color, hardness, and mode of occurrence.

Environment

As an alteration mineral in hydrothermal replacement deposits, usually in arid copper-bearing regions.
 

Rock Type

Sedimentary, Metamorphic

Popularity (1-4)

1

Prevalence (1-3)

2

Demand (1-3)

1