Phenakite | Gemopedia

A rare beryllium mineral, phenakite was named in 1833 from the Greek word for "deceiver," alluding to its similar appearance to quartz. Its crystals are predominantly rhombohedral, and less commonly short and prismatic. Phenakite's rarity, hardness, lack of cleavage and high clarity make it a great option for collectors.
Alternate
Names
Phenacite
Colors
Colorless To Light Yellow, Light Brown, Pink, Greenish Blue

Phenakite Classification

Common Name

Phenakite

Species

Phenakite

Variety

Colors

Colorless To Light Yellow, Light Brown, Pink, Greenish Blue

Alternate Names

Phenacite

Gemstone Groups

Key Separations

Optic character, SG, birefringence and possibly cleavage and fluorescence

Comments

Phenakite Optical Properties

Transparency

Transparent

Refractive Index

1.654-1.67
Tolerance:(+0.026/-0.004)

Birefringence

0.016

Optic Character

Uniaxial

Optic Sign

Positive

Polariscope Reaction

Doubly Refractive (DR)

Fluorescence

SWUV: Inert to weak pink, light blue or green
LWUV: Inert to weak pink, light blue or green

CCF Reaction

Pleochroism

Dichroic, weak to moderate, varying shades of body color

Dispersion

Strength: weak fire Value: 0.015

Comments

Phenakite Chemistry & Crystallography

Chemical Name

beryllium silicate

Chemical Formula

Be2SiO4

Synthesis

Crystal System

Hexagonal

Classification

Silicate

Nature

Natural

Crystallinity

Crystalline

Comments

Phenakite Characteristic Physical Properties

Hardness

7.5-8

Streak

White

Specific Gravity

2.9-3 Typical:2.95

Toughness

Good

Inclusions

Luster

Vitreous

Stability

Fracture

Conchoidal

Cleavage

Good, in one direction, Poor, in one direction

Comments

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