Photo of Petalite in Processed & Rough Form
Petalite is a mineral with a hardness of 6 out of 10 on the Mohs scale of mineral hardness [?]. These Monoclinicly structured gems are made of lithium aluminum silicate, their full chemical compound being Li2OAl2O38SiO2.
Petalite is a lithium aluminum silicate that is an important ore of lithium.
This mineral forms, rarely, as small crystals, which are commonly twinned. More often, petalite forms as large, cleavable masses. It may be white, grey, pinkish, yellow, or colorless. It is transparent to translucent, with a vitreous to pearly luster, and fuses with difficulty.
It forms in very coarse-grained, acid igneous rocks. It is associated with a number of minerals, including quartz, and lepidolite, spodumene, and other lithium-rich minerals.
Fine, transparent masses are common at Varutrask (Sweden), Bikita (Rhodesia), South Africa, Finland, and Australia. Fine, terminated crystals were found in Norwich, Massachusetts (USA). It is also found in granite on the island of Elba (Italy) and in Wyoming, California, Oxford County-Maine (USA), Russia, Brazil, Zimbabwe, and Namibia.
Varieties are called castor or castorite. There are some rare varieties of petalite cat's eyes.
Petalite is also called lithia-feldspar, and lithium-feldspar.
It is often confused with other colorless gems and glass.
Why is Petalite becoming more valuable?
While historically overlooked, petalite's rarity and connection to lithium has increased collector interest. Fine transparent specimens are increasingly sought after, particularly as lithium minerals gain attention. However, it remains primarily a collector's stone.
What makes Brazilian Petalite unique?
Brazilian petalite, particularly from Minas Gerais, is known for exceptional clarity and sometimes showing delicate pink hues. These specimens often produce the finest faceted stones and show better transparency than material from other locations.
How can I identify genuine Petalite?
Petalite has perfect cleavage in two directions, moderate hardness (6-6.5), and typically shows a pearly luster. It's often confused with feldspar but can be distinguished by its optical properties and lower specific gravity.
Are pink Petalites natural?
Yes, some petalite naturally shows pale pink coloration, though most specimens are colorless. The pink variety is highly sought after by collectors, particularly from Brazilian and African sources.
Why isn't Petalite used more in jewelry?
Despite its beauty, petalite's perfect cleavage and moderate hardness make it challenging for jewelry use. Most specimens are preserved for mineral collections rather than cut into gemstones. When faceted, it requires protective settings.
What causes the occasional color change effect?
Rare specimens show subtle color changes between natural and artificial light. This phenomenon is not well understood but may relate to trace elements in the crystal structure. These specimens are particularly valued by collectors.
Is Petalite related to Kunzite?
While both are lithium-bearing minerals, petalite and kunzite (spodumene) are different species. They can show similar colors but have distinct crystal structures and properties. Both are valued collector's stones.
The specific gravity [?] for Petalite is 2.42, its refractive index [?] is 1.50-1.51, and its double refraction [?] is 0.014.
History
Petalite derives its name from the Greek "petalon" meaning "leaf." It was discovered in 1800, in Sweden.
Industrial Usages
Petalite mineral was used to manufacture glass-ceramic cooking ware CorningWare. It has been used as a raw material for ceramic glazes.
Petalite crystal is cut as faceted gems and prized by collectors. Some stone shows chatoyancy such as petalite-analcime cat's-eye.
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