Sinhalite | Gemopedia

Sinhalite is named after its discovery location, Sri Lanka, using its Sanskrit name, Sinhala. This rare gemstone was, until recently, only found in Sri Lanka, but is now mined in Tanzania, Madagascar and Burma. Often occurring in green to brown to brownish black hues, it was once mistakenly believed to be a variety of olivine.
Colors
Greenish To Brownish Yellow, Brown, Rarely Light Pink

Sinhalite Classification

Common Name

Sinhalite

Species

Sinhalite

Variety

Colors

Greenish To Brownish Yellow, Brown, Rarely Light Pink

Alternate Names

Gemstone Groups

Key Separations

RI, birefringence, optic character and spectrum

Comments

Misnomer: brown peridot

Sinhalite Optical Properties

Transparency

Transparent - Translucent

Refractive Index

1.668-1.707
Tolerance:(+0.005/-0.003)

Birefringence

0.036-0.039

Optic Character

Biaxial

Optic Sign

Negative

Polariscope Reaction

Doubly Refractive (DR)

Fluorescence

SWUV: Inert
LWUV: Inert

CCF Reaction

Pleochroism

Trichroic, moderate to strong light brown, dark brown, and greenish brown

Dispersion

Strength: moderate fire Value: 0.017

Comments

Sinhalite Chemistry & Crystallography

Chemical Name

magnesium aluminum iron borate

Chemical Formula

MgAlBO4

Synthesis

Crystal System

Orthorhombic

Classification

Borate

Nature

Natural

Crystallinity

Crystalline

Comments

Sinhalite Characteristic Physical Properties

Hardness

6.5-7

Streak

White

Specific Gravity

3.46-3.5 Typical:3.48

Toughness

Good

Inclusions

Sinhalite might have natural inclusions, sillimanite needles and can show iron staining.

Luster

Vitreous

Stability

Fracture

Conchoidal

Cleavage

None

Comments

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