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Material World
Mineral · K(Li,Al)3(Si,Al)4O10(F,OH)2

Lepidolite

A lilac lithium mica — the second lithium ore, and the main mineral source of rubidium and caesium alongside it.

Ore

Lepidolite is a mica with lithium in it, and it is usually a distinctive lilac or pink — the only common mica of that colour, which makes it easy to spot in a pegmatite. Like all micas it splits into thin flexible sheets along one perfect cleavage.

It is the second lithium ore after spodumene, and less used, because it carries fluorine that complicates processing. Its other significance is the elements that ride along: rubidium and caesium substitute for potassium in the mica structure, and lepidolite is where most rubidium comes from.

How it forms

Lepidolite forms in granite pegmatites, the same setting as spodumene and for the same reason: lithium is an awkward ion that most rock-forming minerals reject, so it concentrates into the last fluids to crystallise. Where those fluids are also rich in fluorine, the lithium ends up in a mica rather than a pyroxene.

Medium confidence Weak evidence

How we know: checked recently · only one source, so there is nothing to cross-check it against · stated directly by the source.

How this connects

Where a connection has been confirmed by an outside reference, that reference is named beside it.

is an ore of

  • Lithium — element · the second lithium ore after spodumene, less used because its fluorine complicates processing
  • Rubidium — element · the main mineral source of rubidium, which substitutes for potassium in the mica

is an input to

is a component of

  • Pegmatite — rock · an accessory of rare-element pegmatites rather than a defining constituent — the lilac mica, in the more fluorine-rich bodies

is an alternative to

  • Spodumene — mineral · as hard-rock lithium ore. Spodumene is richer and the industry standard; lepidolite carries fluorine that complicates the roast and rubidium and caesium that can pay for the trouble

contains

  • Aluminium — element · substitutes within a solid solution — an individual specimen may hold little of it
  • Fluorine — element · substitutes within a solid solution — an individual specimen may hold little of it
  • Hydrogen — element · substitutes within a solid solution — an individual specimen may hold little of it
  • Potassium — element
  • Lithium — element · substitutes within a solid solution — an individual specimen may hold little of it
  • Oxygen — element
  • Silicon — element · substitutes within a solid solution — an individual specimen may hold little of it

Sources

  • Material World
    Our own writing
  • Wikidata
    Wikimedia Foundation · Creative Commons CC0 1.0 Universal (public domain dedication)

Questions this page answers

Where it comes from, and what it becomes

Follow Lepidolite back to what it starts as, and forward into what it becomes. Each step is a documented one — a real route material takes, not a chain of inference.

Downstream — what it becomes

  • Lepidolite → is an ore of (the second lithium ore after spodumene, less used because its fluorine complicates processing) → Lithium → is a source for (as lithium carbonate, which is the traded chemical rather than the metal — from Atacama brine or from Australian spodumene) → Lithium iron phosphate → is used in (in more than half of world cell production, and in almost all stationary storage — the cathode chosen where mass does not bind and price and fire risk do) → Lithium-ion cell → is used in (and portable computing came first by two decades) → Electronics manufacture → is associated with (and the supply chain it produced is the deepest and most concentrated in the world economy) → The semiconductor era complete chain
  • Lepidolite → is an input to (after concentration, as one of the two routes to lithium chloride) → Molten salt electrolysis → produces (from molten magnesium chloride, including the chloride returned by the Kroll process) → Magnesium → is an input to (the reducing agent, recovered afterwards by electrolysing the magnesium chloride by-product) → Kroll process → produces (as sponge, which must then be crushed, melted and cast before it is usable metal) → Titanium → is used as (as titanium dioxide, which consumes more titanium by tonnage than metal production does) → Pigment
  • Lepidolite → is an ore of (the main mineral source of rubidium, which substitutes for potassium in the mica) → Rubidium → is used as (less accurate than caesium and small enough to fly, which is what put atomic clocks into satellites and networks) → Timekeeping
  • Lepidolite → is a component of (an accessory of rare-element pegmatites rather than a defining constituent — the lilac mica, in the more fluorine-rich bodies) → Pegmatite
  • Lepidolite → is an ore of (the second lithium ore after spodumene, less used because its fluorine complicates processing) → Lithium → is used in (the ion that shuttles, and the only part of the cell the name mentions) → Lithium-ion cell → is used in (and portable computing came first by two decades) → Electronics manufacture → is associated with (and the supply chain it produced is the deepest and most concentrated in the world economy) → The semiconductor era complete chain
  • Lepidolite → is an ore of (the second lithium ore after spodumene, less used because its fluorine complicates processing) → Lithium → is used as (the defining material of the rechargeable cell) → Battery electrodes

These are the most distinct paths onward. Lepidolite ends up in others besides.