Lepidolite

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
H2O	4.70%	n/a
LOI	10.00%	n/a
Oxide Weight		476.52
Formula Weight		558.64

Notes

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
5 LOI
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 - Brazil

Lepidolite ore

Lepidolite - Rociada, Mexico

Links

URLs	http://mineral.galleries.com/minerals/silicate/lepidoli/lepidoli.htm Lepidolite at Mineral.galleries.com
URLs	http://webmineral.com/data/Lepidolite.shtml Lepidolite at WebMineral.com
URLs	http://www.mindat.org/show.php?name=Lepidolite Lepidolite at Mindat.org
URLs	http://en.wikipedia.org/wiki/Lepidolite Lepidolite at Wikipedia
Materials	Lepidolite
Materials	Amblygonite
Materials	Petalite
Materials	Spodumene Spodumene is a lithium sourcing feldspar, an alternative to lithium carbonate to supply Li2O to ceramic glazes. Contains up to about 8% Li2O.
Materials	Triphylite
Materials	Mica
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.
Oxides	Li2O - Lithium Oxide, Lithia
Minerals	Lepidolite Although this material is sometimes referred to as a lithium feldspar, it is not a feldspar, but rat

Data

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

By Tony Hansen
Follow me on

Got a Question?

Buy me a coffee and we can talk