Gem library
Lepidolite
The lithium mica, lilac and leafed
Lepidolite is a mica, a mineral that splits into sheets as supple as the pages of a book. Its lilac tone comes from manganese, and the lithium it carries has, these past few years, made people look at it differently.
- Hardness (Mohs)
- 2.5 – 3
- Density
- 2.80 – 2.90
- Crystal system
- Monoclinic
- Refractive index
- 1.525 – 1.590
- Cleavage
- Perfect on {001}
Mineralogical identity
- Family
- Silicates, phyllosilicates, mica group
- Species
- Lepidolite
- Variety
- Lithium-bearing mica
- Chemical formula
- K(Li,Al)₃(Si,Al)₄O₁₀(F,OH)₂
- Crystal system
- Monoclinic
- Classification
- Collector's mineral · ornamental stone
- Rarity
- Common
- Indicative price
- €0.20 – 5/ct
Etymology
From the Greek lepidos, «scale», for a structure of sheets that flake off like fish scales.
Physical & optical properties
- Hardness (Mohs)
- 2.5 – 3
- Density
- 2.80 – 2.90
- Refractive index
- 1.525 – 1.590
- Birefringence
- 0.018 – 0.038
- Cleavage
- Perfect on {001}, into sheets
- Fracture
- Splintery
- Lustre
- Pearly
- Diaphaneity
- Translucent to opaque
- UV fluorescence
- None
- Pleochroism
- Weak
- Colours
- lilac, violet, pink, grey
Formation, geology & history
Formation and geology
Lepidolite forms in granitic pegmatites, those pockets of residual magma where rare elements concentrate at the end of crystallisation. It almost always keeps company with tourmaline, spodumene and beryl: a lepidolite pegmatite is a lithium pegmatite, and prospectors know it. Individual crystals are rare and small; the material usually comes as compact masses of thousands of stacked scales, which give the stone its characteristic glitter. The deposits of Minas Gerais in Brazil and those of California supply most of the ornamental lepidolite on the market.
Lithium, from one century to the next
Lepidolite was the first industrial source of lithium, worked from the nineteenth century for pharmaceutical lithium salts and for speciality glass. It was later displaced by spodumene and above all by South American brines, far cheaper to process. The explosion in battery demand has revived interest: several mining projects are reopening old lepidolite deposits in China, Portugal and Zimbabwe. A collector's piece costing a few euros is therefore, chemically, the same material people now fight over permits for.
Colour and durability
The lilac comes from manganese; the intensity runs from barely tinted grey to a frank violet. The stone is often sold with pink tourmaline rods growing through it, a natural association from the same pegmatite and much sought after in decoration. Its durability must be stated plainly: at hardness 2.5, lepidolite is scratched by a fingernail. Polished slabs keep their pearly sheen if not handled much; jewellery wears quickly. Compact pieces stabilised with resin, common in the trade, hold up better but are no longer quite natural, and that should be said.
How to recognise it
- The sheetingScrape an edge with a fingernail: bright scales come away. No quartz, no fluorite does that. It is the signature of a mica.
- Pearly lustre on the edgeSeen from the side, a lepidolite slab returns a silky, layered reflection rather than a glassy one. Under a loupe the sheeting reads as a stack.
- Weight and feelLight for its bulk (density 2.85) and soft, almost soapy to the touch, unlike violet quartz, which is crisp and cold.
Imitations, treatments & confusions
- Violet fluorite sold as lepidoliteFluorite is transparent, crystallises in cubes and does not sheet. A frequent confusion on beads.
- Resin filled with mica powderMany cheap «lepidolite» slabs are agglomerates. Under a loupe you see a uniform ground with flakes floating in it, instead of a continuous stack.
- Undeclared stabilised stoneResin impregnation is common and legitimate when announced. An abnormally glossy surface and a bead of water that will not soak in are the clues.
Deposits & origins
Brazil (Minas Gerais), United States (California, Maine), Madagascar, Zimbabwe, Russia (Urals), Afghanistan, Czech Republic (Rožná)
Care & precautions
- No water: it seeps between the sheets and lifts them. A dry cloth or soft brush only.
- No ultrasonics or steam, they break the stone up in seconds.
- Avoid prolonged sun, which dulls the lilac.
- Store flat and apart: at hardness 2.5 everything scratches it, including a key in the same pocket.
Traditions & crystal healing
- Chakras
- Third eye · crown
- Zodiac signs
- Libra · Pisces
- Element
- Water
It is presented as a stone of calm and transition, to keep near you through periods of change. Practitioners readily invoke the lithium it contains, but honesty requires saying that lithium locked in a mineral is not bioavailable, and the link is an image rather than a mechanism. Cultural heritage, never medicine.
The virtues described here belong to tradition and cultural heritage. They are in no way medical advice and never replace a consultation.
Frequently asked questions
Can lepidolite go in water?
No. The sheets separate and the stone falls apart. It is one of the few common minerals where the answer is flatly negative.
Is lepidolite dangerous to handle?
No, provided you do not breathe its dust, which is true of any mineral you saw or grind. A polished piece needs no precautions.
Why are some slabs so shiny?
Either the stacked scales are catching the light, or the piece has been resin-impregnated. A serious dealer will tell you which.
Tools for this stone
Lepidolite: only the tools this stone actually concerns, each carrying the value read on this page.