Alabaster Gem Guide and Properties Chart

Alabaster is a fine-grained massive form of gypsum. Alabaster ranges from white to yellow, pink, and brown. Due to its porosity it is often dyed. It has been used for centuries for statues, carvings, and other ornamental purposes. Treated alabaster is used as a marble simulant. Due to its extreme softness, it is ideal for fashioning into works of art.

General Information

Classification
Optical Properties
Characteristic Physical Properties
Chemistry & Crystallography

Common Name

Alabaster

Species

Gypsum

Transparency

Translucent - Opaque

Refractive Index

1.520-1.529
Tolerance:(+0.001/-0.001)

Birefringence

0.009- 0.010

Optic Character

Biaxial

Optic Sign

Positive

Polariscope Reaction

Aggregate (AGG), Doubly Refractive (DR)

Fluorescence

SWUV: Inert to weak brownish to greenish white
LWUV: Inert to weak brownish to greenish white

Pleochroism

None

Hardness

1.5-2

Streak

White

Specific Gravity

2.250-2.350 Typical:2.300

Toughness

Poor

Inclusions

Alabaster is sometimes banded, veined,or patterned like marble and it is often dyed and has a poor polish.

Luster

Waxy, Subvitreous

Stability

Fair

Fracture

Granular

Cleavage

None

Chemical Name

hydrous calcium sulfate

Chemical Formula

CaSO₄-₂H₂O

Crystal System

Monoclinic

Chemistry Classification

Sulfate

Alabaster Colors

Brown
Pink
White

Alternate Names

Alabastrite

Countries of Origin

Ecuador; Russian Federation; Japan; United States of America; United Kingdom of Great Britain and Northern Ireland; Switzerland; Spain; Austria; Poland; Italy; Slovakia; France; Peru; Germany

Care

Due to its soft nature alabaster needs to be kept away from harder materials that will damage its surface. Alabaster will turn cloudy if exposed to heat.