Crystal Ulexite

Chemical Formula

NaCaB₅O₉ · 8H₂O

Composition

Hydrous sodium calcium borate

Color

White to light gray

Streak

White

Hardness

2.5

Crystal System

Triclinic

Crystal Forms 
and Aggregates

Rarely in noticeable crystals; occurs in groups of tiny crystals in rounded or lenticular aggregates. It is most commonly seen as compact, parallel, fibrous veins. Occasionally encrusting and as radialcompactions of thin crystals.

Transparency

Transparent to translucent

Specific Gravity

1.6 - 1.9

Luster

Silky

Cleavage

1,1 - prismatic ; 2,1 - basal

Fracture

Uneven to splintery

Tenacity

Brittle

Complex Tests

Slightly soluble in hot water. (This effect is very weak and is almost unnoticeable.)

In Group

Borates; Hydrous Borates

Striking Features

Silky luster, low weight and hardness.

Environment

Borax evaporite deposits in dry lakes of arid regions.

Rock Type

Sedimentary

Popularity (1-4)

2

Prevalence (1-3)

1

Demand (1-3)

1