Petalite
A variety of Minerals
What is Petalite?
Petalite, also known as castorite, is a lithium aluminium phyllosilicate mineral LiAlSi4O10, crystallizing in the monoclinic system. Petalite occurs as colorless, pink, grey, yellow, yellow grey, to white tabular crystals and columnar masses. Occurs in lithium-bearing pegmatites with spodumene, lepidolite, and tourmaline. Petalite is an important ore of lithium, and is converted to spodumene and quartz by heating to ~500 °C and under 3 kbar of pressure in the presence of a dense hydrous alkali borosilicate fluid with a minor carbonate component. Petalite (and secondary spodumen formed from it) is lower in iron than primary spodumen making it a more useful source of lithium in e.g. the production of glass. The colorless varieties are often used as gemstones.
Optical Properties
- Refractive Index
- 1.502-1.523
- Birefringence
- 0.012-0.016
- Pleochroism
- Absent
- Optical Character
- Biaxial positive
- Dispersion
- 0.0141
Market Value Factors
Pricing varies for every rock and mineral, so use these universal factors to gauge Petalite before comparing listings or appraisals.
Size & Weight
Larger, intact specimens usually command higher prices.
Rarity & Demand
Scarce material or popular varieties sell at a premium.
Condition & Finish
Chips, repairs, and heavy wear lower value; clean prep helps.
Treatment & Provenance
Untreated specimens with documented locality are prized.
Petalite Localities Map
See where Petalite is found with a localities map, collecting zones, and geology context. Generate a sample map preview below.
The Meaning
Petalite is a birthstone for the zodiac sign of Leo.
Key Characteristics
Formation of Petalite
Discovered in 1800, by Brazilian naturalist and statesman Jose Bonifacio de Andrada e Silva. Type locality: Utö Island, Haninge, Stockholm, Sweden. The name is derived from the Greek word petalon, which means leaf (perfect cleavage). Economic deposits of petalite are found near Kalgoorlie, Western Australia; Aracuai, Minas Gerais, Brazil; Karibib, Namibia; Manitoba, Canada; and Bikita, Zimbabwe. The first important economic application for petalite was as a raw material for the glass-ceramic cooking ware CorningWare. It has been used as a raw material for ceramic glazes.
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Quick Facts
Physical Properties
- Color
- Colourless, white, grey, pink
- Hardness (Mohs)
- 6.5
- Density
- 2.4 g/cm³
- Streak
- White
Chemical Properties
- Chemical Formula
- LiAl(Si4O10)
- Elements
- Al, Li, O, Si
Also Known As
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Petalite FAQs
How do I identify Petalite?
Petalite can be identified by its hardness of 6.5 on the Mohs scale, Colourless color. Look for these key characteristics when examining specimens.
What color is Petalite?
Petalite typically appears in Colourless, white, grey, pink. Color can vary depending on impurities and formation conditions.
How hard is Petalite?
Petalite has a hardness of 6.5 on the Mohs scale. This gives it moderate hardness.
What is the formation of petalite of Petalite?
Discovered in 1800, by Brazilian naturalist and statesman Jose Bonifacio de Andrada e Silva. Type locality: Utö Island, Haninge, Stockholm, Sweden. The name is derived from the Greek word petalon, which means leaf (perfect cleavage). Economic deposits of petalite are found near Kalgoorlie, Western Australia; Aracuai, Minas Gerais, Brazil; Karibib, Namibia; Manitoba, Canada; and Bikita, Zimbabwe. The first important economic application for petalite was as a raw material for the glass-ceramic cooking ware CorningWare. It has been used as a raw material for ceramic glazes.
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