- Lepidolite is a lithium-rich mica mineral with the idealized chemical formula K(Li,Al)₃(Si,Al)₄O₁₀(F,OH)₂. It is one of the most important sources of lithium and is well-known for its scaly or platy habit, typical of mica minerals, as well as its attractive pink to lilac or purple coloration, which makes it a favorite among mineral collectors.
- Lepidolite belongs to the phyllosilicate group, characterized by sheet-like crystal structures, and is typically found in granitic pegmatites—coarse-grained igneous rocks that often host other lithium-bearing minerals like spodumene and petalite.
- Structurally, lepidolite has a layered arrangement of silicate tetrahedra and is chemically complex, with a composition that allows for considerable substitution of elements. Lithium can occupy positions normally filled by aluminum, while fluorine and hydroxyl groups can also vary. This variability leads to a range of compositions, which has resulted in lepidolite being classified more as a mineral series than a single fixed compound. Despite this, its high lithium content—often up to 3–5% by weight—makes it a commercially viable lithium ore, especially in regions where hard-rock mining is practiced.
- Lepidolite forms in pegmatitic environments, where it crystallizes from the last, volatile-rich fluids of granitic magma. These fluids are rich in rare elements such as lithium, rubidium, and cesium, many of which can be incorporated into lepidolite’s structure. In addition to lithium, lepidolite is also a potential source of rubidium and cesium, both of which are valuable in high-tech and industrial applications. The mineral is typically associated with other rare-element minerals such as tourmaline, beryl, and topaz, and often occurs in massive aggregates or fine-grained plates rather than large, distinct crystals.
- In industrial applications, lepidolite has historically been used as a lithium source for glass and ceramic production, and in the past, it was even used as a source of lithium for medications (e.g., lithium carbonate used to treat bipolar disorder). However, with the growing demand for lithium in lithium-ion batteries, interest in lepidolite mining has revived, especially as higher-grade spodumene ores become more limited. While it is more difficult and costly to extract lithium from lepidolite than from spodumene or brine sources, advancements in leaching and processing technologies are making lepidolite increasingly viable as part of the global lithium supply chain.
- Aesthetically, lepidolite is prized in the gemstone and decorative stone markets. Its unique shimmer—caused by light reflecting off its thin, flexible mica layers—and its soft purple hues make it a popular material for cabochons, carvings, and metaphysical crystals. However, it is relatively soft (with a Mohs hardness of about 2.5 to 3.5), so its use in jewelry is mostly limited to pendants or display pieces rather than rings or bracelets that require greater durability.
