Lepidolite
Potassium lithium aluminium silicate (K(Li,Al)3(Si,Al)4O10(F,OH)2)
A soft lithium-bearing mica with a lilac to purple color and pearly, flaky sheen, an important ore of lithium.
- Mohs hardness
- 2.5-3
- Color
- Lilac, pink, purple to gray, with a pearly sheen
- Type
- mineral
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Overview
Lepidolite is a lithium-rich member of the mica group, instantly recognizable by its lilac, pink to purple color and pearly, scaly sheet structure. The color is largely due to manganese and lithium content. It often occurs as masses of fine glittering flakes or as books of stacked sheets.
As a mica it is very soft and splits readily into thin, flexible, elastic sheets along a single perfect cleavage. It is an important ore of lithium and the alkali metals rubidium and cesium.
Lepidolite is commonly seen in jewelry and decor as compacted masses, sometimes intergrown with pink tourmaline or quartz (lepidolite in quartz).
Formation & geology
Lepidolite forms almost exclusively in granitic pegmatites, the coarse-grained, late-stage igneous rocks enriched in rare elements like lithium, rubidium and cesium. It crystallizes from residual, volatile-rich melts and is frequently associated with other lithium minerals such as spodumene, amblygonite and pink (lithium) tourmaline.
Because it concentrates lithium, it is mined as an ore in such pegmatites. Major sources include Brazil (Minas Gerais), the USA (California, Maine), Madagascar, the Czech Republic, Russia and Zimbabwe.
How to identify it
Lepidolite is lilac to pink-purple with a pearly to vitreous luster and a distinctive flaky, sparkly appearance from countless tiny mica plates. It is very soft (hardness 2.5-3) and can be scratched by a fingernail or coin; it splits into thin flexible elastic sheets along one perfect cleavage. Streak is white.
Look-alikes: Purpurite and charoite are harder and lack the micaceous sheets. Fluorite is harder (4) with cubic cleavage. Other micas (muscovite) are not purple. The soft, peeling lavender flakes and one-direction cleavage are the diagnostic clues; massive lepidolite jewelry stones are often stabilized.
Uses & significance
Lepidolite is economically important as an ore of lithium (used in batteries, glass and ceramics) and of rubidium and cesium. Industrially, lithium and these alkali metals are extracted from lepidolite-rich pegmatites.
As an ornamental stone, massive lepidolite is tumbled, carved and made into beads and palm stones, often stabilized because of its softness. Specimens with pink tourmaline are collectible.
Metaphysically it is marketed as a calming stone of peace and emotional balance, partly because of its lithium content, though no medicinal benefit from handling it is scientifically demonstrated.
Frequently asked questions
Does lepidolite really contain lithium?
Yes, lepidolite is a lithium-bearing mica and an actual ore of lithium, but the lithium is chemically bound in the mineral and is not absorbed by handling it.
Why is lepidolite so soft and flaky?
As a member of the mica group it has one perfect cleavage and splits into thin elastic sheets, giving it a low hardness of about 2.5-3.
Can lepidolite go in water?
It is best to avoid water; lepidolite is soft, flaky and can flake apart or degrade with prolonged moisture, so clean it dry.
What is lepidolite in quartz?
It is lepidolite that has grown together with or been encased in quartz, producing a more durable purple-flecked stone suitable for tumbling and jewelry.
Lepidolite guides
In-depth guides for identifying, valuing, and understanding Lepidolite.
Lepidolite identified by the community
Real specimens identified with Rock Identifier.
