Petalite

Petalite

By Tim Matthews, JD, FGA, GG, DGA,
CEO and President of JTV (retired)
Published: June 2014
Modified: December 2023
Petalite Polished Petalite Rough Petalite Jewelry

Faceted petalite gems and specimens are prized by gemstone and mineral collectors. Petalite's name is derived from the Greek petalos (leaf), referring to its perfect cleavage. Colorless material is common, and large crystals have been mined. Other petalite colors include white to yellow or gray, yellowish green to light green and pink. Crystals range from transparent to translucent and are prized for their good clarity. Faceted gems aren't often seen due to petalite's cleavage planes.

General Information

Common Name
Petalite
Species
Petalite
Transparency
Translucent-Transparent
Refractive Index
1.504-1.523 Tolerance: (+0.006/-0.002)
Birefringence
0.12-0.16
Optic Character
Biaxial
Optic Sign
Positive
Polariscope Reaction
Doubly Refractive (DR)
Fluorescence
SWUV: Inert to yellowish white
LWUV: Inert to weak orange or yellowish white
Pleochroism
Unobservable
Hardness
6-6.5
Streak
White
Specific Gravity
2.400-2.422 Typical:2.400
Toughness
Poor
Luster
Vitreous, Pearly
Fracture
Subconchoidal
Cleavage
Perfect, in one direction, Poor, in one direction
Chemical Name
lithium aluminum silicate
Chemical Formula
LiAlSi4O10
Crystal System
Monoclinic
Chemistry Classification
Silicate

Petalite Colors

  • Blue Petalite
    Blue
  • Brown Petalite
    Brown
  • Colorless Petalite
    Colorless
  • Gray Petalite
    Gray
  • Green Petalite
    Green
  • Pink Petalite
    Pink
  • White Petalite
    White
  • Yellow Petalite
    Yellow

Alternate Names

Castorite

Countries of Origin

Myanmar; Afghanistan; Russian Federation; Angola; Czechia; United States of America; Egypt; Kazakhstan; United Kingdom of Great Britain and Northern Ireland; Portugal; Sweden; Mozambique; Pakistan; Unknown; China; Brazil; France; Argentina; Japan; Ukraine; Spain; Canada; Namibia; Finland; Italy; South Africa; Zimbabwe; Australia; Ethiopia

Care

Normal care for untreated material. In CVD caoated material color may be affected by polishing, recutting, ultrasonic cleaners, alcohol, and harsh chemicals.