Colemanite
2CaO.2B2O3.5H2O
Chemistry
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Volatiles
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Links to Other Materials
- Ulexite - Related
- Turkish Colemanite - Related
- ABC Colemanite - Related
- Colemanite 38 - Related
- Cache
Miscellaneous
- Family: Flux Source
- Region: North America
- Mined At: Unspecified
- Raw Mineral: Yes
- Generic: Yes
Notes
(Richard Willis)
Colemanite has been a popular natural source of insoluble boron for many decades. It is similar to Ulexite in its oxide contribution to glazes (although the latter sources Na2O also). Frits are used as boron sources in industry whereas potters and smaller companies have used Colemanite.
Colemanite does not melt as low or as uniformly as Ulexite. Gerstley Borate contained significant amounts of Colemanite and the website at www.gerstleyborate.com has lots of information on this and related minerals. Pure colemanite, however, is much higher in B2O3 than Gerstley Borate.
Colemanite is available from Turkey, Chile and California. The chemistry of these varies quite a bit, the one shown here is an average since none of the available materials have the theoretical chemistry of 27.3 CaO, 50.8 B2O3 and 21.9 LOI.
Natural colemanite decrepitates. If this 'spangling' is a problem on vertical surfaces, screen out any materials coarser than 200 mesh, or ball mill the glaze. Gum or other binders also help.
Data
- Solubility: in HCl but not in water
- Density: 2.4
- Melting Point (MP): 1050C
- Hardness (Moh): 4.5
- Specific Gravity: 2.95
- Specific Gravity: 2.95
- Hardness (Moh): 4.5
- Melting Point (MP): 1050C
- Density: 2.4
- Solubility: in HCl but not in water
URLs
- GerstleyBorate.com - www.gerstleyborate.com
- Wikipedia Definition - http://en.wikipedia.org/wiki/Colemanite
Suppliers
- ETI Holding A.S.
- Generic
- Rio Tinto Borax
Authors
- Tony Hansen (Owner)
XML
<?xml version="1.0" encoding="UTF-8"?>
<material name="Colemanite" descrip="2CaO.2B2O3.5H2O" generic="1" rawmineral="1" searchkey="Calcium Borate" loi="0.00">
<families>
<family name="Flux Source"/>
</families>
<regions>
<region name="North America"/>
</regions>
<oxides>
<oxide symbol="CaO" name="Calcium Oxide, Calcia" status="" percent="27.000" tolerance=""/>
<oxide symbol="MgO" name="Magnesium Oxide, Magnesia" status="" percent="1.500" tolerance=""/>
<oxide symbol="Al2O3" name="Aluminum Oxide, Alumina" status="" percent="0.500" tolerance=""/>
<oxide symbol="B2O3" name="Boric Oxide" status="" percent="43.000" tolerance=""/>
<oxide symbol="SiO2" name="Silicon Dioxide, Silica" status="" percent="1.000" tolerance=""/>
<oxide symbol="SiO2" name="Silicon Dioxide, Silica" status="" percent="4.000" tolerance=""/>
<oxide symbol="Fe2O3" name="Iron Oxide, Ferric Oxide" status="" percent="0.300" tolerance=""/>
</oxides>
<volatiles>
<volatile symbol="" name="" percent="22.000" tolerance=""/>
</volatiles>
<references>
<reference name="seealso" reason=""/>
<reference name="seealso" reason=""/>
<reference name="seealso" reason=""/>
<reference name="seealso" reason=""/>
</references>
<suppliers>
<supplier name="ETI Holding A.S." country="TR" url="http://www.etimine.com/" label=""/>
<supplier name="Generic" country="" url="" label=""/>
<supplier name="Rio Tinto Borax" country="US" url="http://www.borax.com" label=""/>
</suppliers>
<notes>
<note>Colemanite has been a popular natural source of insoluble boron for many decades. It is similar to Ulexite in its oxide contribution to glazes (although the latter sources Na2O also). Frits are used as boron sources in industry whereas potters and smaller companies have used Colemanite.
Colemanite does not melt as low or as uniformly as Ulexite. Gerstley Borate contained significant amounts of Colemanite and the website at www.gerstleyborate.com has lots of information on this and related minerals. Pure colemanite, however, is much higher in B2O3 than Gerstley Borate.
Colemanite is available from Turkey, Chile and California. The chemistry of these varies quite a bit, the one shown here is an average since none of the available materials have the theoretical chemistry of 27.3 CaO, 50.8 B2O3 and 21.9 LOI.
Natural colemanite decrepitates. If this \'spangling\' is a problem on vertical surfaces, screen out any materials coarser than 200 mesh, or ball mill the glaze. Gum or other binders also help.</note>
</notes>
<testdata>
<testitem testname="4" value="in HCl but not in water"/>
<testitem testname="4" value="2.4"/>
<testitem testname="4" value="1050C"/>
<testitem testname="4" value="4.5"/>
<testitem testname="4" value="2.95"/>
<testitem testname="4" value="2.95"/>
<testitem testname="4" value="4.5"/>
<testitem testname="4" value="1050C"/>
<testitem testname="4" value="2.4"/>
<testitem testname="4" value="in HCl but not in water"/>
</testdata>
</material>
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