Emerald

Chemical Formula

Be3Al2SiO6

Composition

Beryllium aluminum silicate

Color

Green to emerald-green

Streak

Colorless

Hardness

7.5 - 8

Crystal System

Hexagonal

Crystal Forms 
and Aggregates

Emerald often crystallizes in perfect, six-sided hexagons. Crystals are usually as individual prismatichexagons. Less commonly in short, stubby crystals and crystal plates. The bases of Beryl crystals are usually flat; pyramidal terminations are very  rare. Also occurs in columnar aggregates and in massive. Occasionally in drusy or platy aggregates and as bundles of thin, long crystals. Crystals may be striatedlengthwise.

Transparency

Transparent to opaque

Specific Gravity

2.6 - 2.9

Luster

Vitreous

Cleavage

3,1 - basal

Fracture

Uneven to conchoidal

Tenacity

Brittle

In Group

Silicates; Cyclosilicates

Striking Features

Emerald green color and hexagonal crystal habit.

Environment

In granite pegmatites and in metamorphosed mica schists.

Rock Type

Igneous, Metamorphic

Popularity (1-4)

1

Prevalence (1-3)

3

Demand (1-3)

1