Lepidolite
A standard material in Glazecalc's library: its oxide analysis, unity contribution and hazards.
What it is
- Kind
- Feldspars and stones
- Status
- Discontinued
- Formula
- LiF•KF•Al₂O₃•3SiO₂ (Digitalfire's formula)
- Also called
- Lithium mica, Lepidolite (lithium mica)
- Sold in
- US
- Similar materials
- Spodumene (Laguna) , Petalite , Lithium Carbonate
- Source
- Digitalfire: Lepidolite
A fluorine-bearing lithium-potassium mica, long unavailable to US potters. There is no direct replacement; supply the Li2O from spodumene, petalite or lithium carbonate, and the K2O from a potash feldspar.
Jeff Zamek's 1997 guide to substitutions in Ceramics Monthly already called it discontinued.
Oxide analysis and unity formula
Glazecalc has the analysis of Lepidolite as weight percent of the raw material. The unity contribution is the moles of each oxide in the amount of Lepidolite that holds 1.0 mole of flux, which is how Glazecalc adds it into a recipe's unity formula.
| Oxide | Weight % | Unity contribution |
|---|---|---|
| K₂O | 7.3 | 0.436 |
| Li₂O | 3 | 0.564 |
| Al₂O₃ | 26.9 | 1.483 |
| SiO₂ | 47.7 | 4.463 |
- Equivalent weight
- 562.1
- Fired weight
- 479.47
- Loss on ignition
- 14.7%
The equivalent weight is the grams of Lepidolite that hold 1.0 mole of flux. The fired weight is what is left of that after firing.
Hazards and safety
Hazards: Contains fluorine, which is released as fumes during firing and can cause glaze bubbles and pitting; ventilate the kiln.
Use it in a recipe
Add Lepidolite to a recipe in the Glazecalc calculator to see what it does to a glaze's unity formula.