Lazulite | Gemopedia

This mineral species can be opaque to crystalline transparent. The color of lazulite ranges from medium to dark greenish blue to violet blue and is often mottled with white. When fashioned into gems, finished stones typically weigh less than 5 carats. A separate mineral species, lazulite should not be confused with lazurite or azurite.
Alternate
Names
Bluespar
Colors
Medium To Dark Greenish Blue To Violet Blue Sometimes Mottled With White

Lazulite Classification

Common Name

Lazulite

Species

Lazulite

Variety

Colors

Medium To Dark Greenish Blue To Violet Blue Sometimes Mottled With White

Alternate Names

Bluespar

Gemstone Groups

Key Separations

RI, birefringence and optic character

Comments

Lazulite Optical Properties

Transparency

Transparent - Opaque

Refractive Index

1.612-1.643
Tolerance:(+0.005/-0.005)

Birefringence

0.031

Optic Character

Biaxial

Optic Sign

Negative

Polariscope Reaction

Doubly Refractive (DR)

Fluorescence

SWUV: inert
LWUV: inert

CCF Reaction

Pleochroism

Trichroic, strong dark violetish blue, colorless, and light blue

Dispersion

Strength: none

Comments

Lazulite Chemistry & Crystallography

Chemical Name

basic magnesium aluminum phosphate

Chemical Formula

MgAl2(PO4)2(OH)2

Synthesis

Crystal System

Monoclinic

Classification

Phosphate

Nature

Natural

Crystallinity

Crystalline

Comments

Lazulite Characteristic Physical Properties

Hardness

5-6

Streak

White

Specific Gravity

3.08-3.17 Typical:3.09

Toughness

Poor

Inclusions

Transparent material is highly included. Aggregate lazulite material will have a mottled appearance with white areas.

Luster

Vitreous

Stability

Fracture

Granular, Uneven

Cleavage

Good, in one direction, Poor, in one direction

Comments

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