Petalite
Formula: LiAlSi4O10 or Li2O.Al2O3.8SiO2
| DENS - Density (Specific Gravity) |
2.45 |
| COLE - Co-efficient of Linear Expansion |
0.15 |
| MLPT - Melting Point (MP) |
1350C M |
Petalite is a lithium aluminum silicate mineral (more simply a lithium feldspar) that is commonly used in clay bodies. It is valuable because it provides an insoluble source of lithium (lithium carbonate is soluble) and has the highest Li2O:Al2O3 ratio of any natural mineral. Lithium is a strong alkaline flux and is effective over all temperature ranges. It and imparts lower expansion and gives unique color response to copper and cobalt in glazes. Some commercial versions have a chemistry that fairly closely matches the theoretical chemistry given here.
Petalite is most prized for its mineralogical properties. It is especially valuable in imparting thermal shock resistance to clay bodies because it has almost zero expansion when heated above 700C. Bodies with 60%+ petalite can take a direct flame and rapid water cooling without failure. To make a plastic clay body mix petalite with as much ball clay as needed. For a casting body, use as much kaolin as needed to achieve the desired casting properties. Bentonite can be added to either type of body to increase the petalite proportion.
One serious problem with low expansion petalite bodies is that it is very difficult to achieve glaze fit. All common glazes will craze. This is compounded at lower temperatures where the limited low-expansion silica and alumina necessary for melting raises glaze expansion. For some low-expansion bodies, it is almost impossible to match a glaze. Flame ware bodies can be made with 50-60% petalite.
Petalite can be used to create low expansion glazes. It is suitable for white and transparents as well because of the low iron content. It does not present the frothing problems sometimes associated with spodumene and helps improve brightness. One formula suggested by Val Cushing is petalite 76.9, talc 14.2, whiting 3.4, kaolin 5.5. This glaze is claimed to have an expansion of 0.8 x 10 -6 and fires cone 9 to 12 with a silky surface.
Spodumene and lepidolite also provide insoluble sources of lithium. However, spodumene is more refractory, thus producing more porous fired results. If a body's range needs to be extended, spodumene can thus be added in preference to silica. Petalite is slightly more refractory than lepidolite.
P.C.E.: 15
P.C.E. 45% petalite:55% F4 Feldspar: 4
P.C.E. 45% petalite:55% Nepheline Syenite: 2
A petalite clay body can be made by combining petalite and ball clay or kaolin in proportions that provide a good compromise between high petalite content and necessary plasticity.
A substitute for petalite can be made from 25% feldspar and 75% spodumene.
Out Bound Links
- (URLs)
Petalite at Wikipedia
http://en.wikipedia.org/wiki/Petalite - (Materials - Related)
Spodumene - Li2O.Al2O3.4SiO2 or LiAl(Si2O6)
- (Hazards - General)
Fluorine Gas
Hazards of this material in the ceramic industry a... - (Typecodes)
1: GNM - Generic Material
- (Typecodes)
1: FEL - Feldspar
- (MDT - Member)
Europe
Countries of Eastern Europe and former Soviet Unio... - (MDT - Member)
Australia
We are working on this database and would apprecia... - (MDT - Member)
Asia
All of Asia including Turkey, Russia, Indosnesia, ... - (MDT - Member)
Africa
All of continental Africa. We are working on this ... - (MDT - Member)
Latin and South America
Latin America and South America. We are working on... - (MDT - Member)
New Zealand
We are working on this database and would apprecia... - (MDT - Member)
North America
The decision about what materials to include in th... - (MDT - Member)
Ron Roy
This is the traditional Ron Roy materials file. He... - (MDT - Member)
UK
We are working on this database and would apprecia... - (Typecodes - Area of use)
1: DEN - Materials used in Denmark
In Bound Links
- (Materials - Related)
Amblygonite - Li.AlF.PO4 - Lithium alumino-fluophosphate
- (Materials - Related)
Lepidolite - LiF.KF.Al2O3.3SiO2
Lithium Mica
- (Materials - Related)
Triphylite
LiFePO4
- (Oxides - Material source)
Li2O - Lithium Oxide, Lithia
XML for Import into INSIGHT
<?xml version="1.0" encoding="UTF-8"?>
<material name="Petalite" descrip="" searchkey="" loi="0.00" casnumber="1302-66-5">
<oxides>
<oxide symbol="Li2O" name="Lithium Oxide, Lithia" status="U" percent="4.865" tolerance=""/>
<oxide symbol="Al2O3" name="Aluminum Oxide, Alumina" status="" percent="16.650" tolerance=""/>
<oxide symbol="SiO2" name="Silicon Dioxide, Silica" status="" percent="78.485" tolerance=""/>
</oxides>
</material> | 
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