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Alternate Names: Lithium Mica

Oxide Analysis Formula
K2O 7.30% 0.43
Li2O 3.00% 0.57
Al2O3 26.90% 1.48
SiO2 47.70% 4.45
Oxide Weight 476.52
Formula Weight 558.64


It has a lower fusion point than most high temperature feldspars. The fluorine content can cause problems with glaze bubbles and surface pitting.

It is tricky to establish a formula weight and analysis for this material. Here are some of the factors:
-LOI varies, but we have assumed 5% water in this example.
-Lepidolite does not actually contain Li2O, it has to absorb oxygen from the atmosphere or other materials during firing since the Li is bonded to F.
-Fluorine is bonded to potassium so oxygen has to be absorbed to create K2O.
-For both Li and K only 1/2 of a molecule per input molecule of lepidolite will be yielded.
-In a complete oxidation firing all of the fluorine will volatilize and none will be in the final glass. However in real world conditions neither of these is likely to happen completely, and in a reduction firing neither may happen at all. In this case we are assuming it is all LOI.

Given the above assumptions, an input of LiF.KF.Al2O3.3SiO2 would yield:
1/2 Li2O
1/2 K2O
2 F
1 Al2O3
3 SiO2
Considering the F as LOI we would have the chemistry quoted here.

To properly handle a material like this in glaze chemistry fluorine conversion factors have to be employed.

Related Information

Lepidolite Stone

Lepidolite ore

Lepidolite ore close-up


Lepidolite at
Lepidolite at
Lepidolite at
Lepidolite at Wikipedia
Minerals Lepidolite
Oxides Li2O - Lithium Oxide, Lithia
Materials Mica
Materials Lepidolite
Materials Amblygonite
Materials Petalite
Materials Spodumene
Materials Triphylite
Hazards Lithium Toxicology
Typecodes Generic Material
Generic materials are those with no brand name. Normally they are theoretical, the chemistry portrays what a specimen would be if it had no contamination. Generic materials are helpful in educational situations where students need to study material theory (later they graduate to dealing with real world materials). They are also helpful where the chemistry of an actual material is not known. Often the accuracy of calculations is sufficient using generic materials.
Typecodes Feldspar
The most common source of fluxes for high and medium temperature glazes and bodies.


Density (Specific Gravity)3.00
Frit Melting Range (C)1150-1300C

By Tony Hansen

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