Sugilite | Gemopedia

Sugilite belongs to a class of minerals known as silicates and is a member of the milarite group. A relatively recent addition to the realm of gemstones, sugilite was discovered in 1944 by a Japanese geologist, Ken-ichi Sugi. The mineral is named in his honor. The original find was a yellowish brown variety that was of no interest to the jewelry industry. It was not until 1979 that the first massive aggregates, exhibiting a rich purple color, were discovered in a South African manganese mine. This material was attractive and gained the attention of the gemstone industry. It is predominantly found in the form of cabochons of various shapes and sizes, but has also been used as a component in intarsia jewelry. It is sometimes carved into decorative objects and fashioned into beads.
Alternate
Names
Royal Azel, Royal Lavulite
Colors
Red-Purple To Bluish Purple, Rarely Pink

Sugilite Classification

Common Name

Sugilite

Species

Sugilite

Variety

Colors

Red-Purple To Bluish Purple, Rarely Pink

Alternate Names

Royal Azel, Royal Lavulite

Gemstone Groups

Key Separations

Intense purplish color, RI, spectrum and SG

Comments

Might show RI of 1.54 due to quartz impurities Misnomer: purple turquoise

Sugilite Optical Properties

Transparency

Semitransparent - Opaque

Refractive Index

1.607-1.61
Tolerance:(+0.001/-0.002)

Birefringence

0.003

Optic Character

Uniaxial

Optic Sign

Negative

Polariscope Reaction

Doubly Refractive (DR)

Fluorescence

SWUV: Inert
LWUV: Inert

CCF Reaction

Pleochroism

None

Dispersion

Comments

Sugilite Chemistry & Crystallography

Chemical Name

potassium sodium lithium iron manganese silicate

Chemical Formula

(K,NA)(Na,Fe)2(Li2Fe)Si12O30

Synthesis

Crystal System

Hexagonal

Classification

Silicate

Nature

Natural

Crystallinity

Crystalline to Aggregate

Comments

Sugilite Characteristic Physical Properties

Hardness

5.5-6.5

Streak

White

Specific Gravity

2.69-2.79 Typical:2.74

Toughness

Good

Inclusions

Sugilite might have banded appearance.

Luster

Vitreous

Stability

Fracture

Granular

Cleavage

None

Comments

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