Alabaster | Gemopedia

Alabaster is a fine grained massive form of gypsum. Alabaster ranges from white to yellow, green and brown, but because of its porosity, it is often dyed a snow white color which resembles marble. It has been used for centuries for statues, carvings and other ornamental purposes. Due to its extreme softness, it is ideal for fashioning into works of art.
Alternate
Names
Alabastrite
Colors
White, Gray, Pink, Reddish, Greenish, Yellow, Brown, Black Veins, Color Concentrations

Alabaster Classification

Common Name

Alabaster

Species

Gypsum

Variety

Alabaster

Colors

White, Gray, Pink, Reddish, Greenish, Yellow, Brown, Black Veins, Color Concentrations

Alternate Names

Alabastrite

Gemstone Groups

Key Separations

Appearance, RI and SG. Poor polished surface due to low mohs hardness.

Comments

Alabaster Optical Properties

Transparency

Translucent - Opaque

Refractive Index

1.52-1.529
Tolerance:(+0.001/-0.001)

Birefringence

0.009-0.01

Optic Character

Biaxial

Optic Sign

Positive

Polariscope Reaction

Doubly Refractive (DR)

Fluorescence

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

CCF Reaction

Pleochroism

None

Dispersion

Comments

Alabaster Chemistry & Crystallography

Chemical Name

hydrous calcium sulfate

Chemical Formula

CaSO4-2H2O

Synthesis

Crystal System

Monoclinic

Classification

Sulfate

Nature

Natural

Crystallinity

Crystalline

Comments

Alabaster Characteristic Physical Properties

Hardness

1.5-2

Streak

White

Specific Gravity

2.25-2.35 Typical:2.3

Toughness

Poor

Inclusions

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

Luster

Waxy

Stability

Fair

Fracture

Granular

Cleavage

None

Comments

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