Volcanic Ash
Chemistry
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Volatiles
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Links to Other Materials
Miscellaneous
- Family: Flux Source
- Region: North America
- Mined At: Unspecified
- Raw Mineral: No
- Generic: Yes
Notes
Pumicite is composed of minute particles of volcanic glass. Deposits resulted from volcanic eruption blowing large quantities of material into the air which settled in layers, sometimes in thicknesses which compressed to 30 feet or more. Volcanic ash particles are non-crystalline due to the quick cooling during formation. This material thus takes on the unique melting properties associated with a glass.
The chemistry is similar to granite or ryolite. Raw color varies and deposits can be found over wide areas of the central and western areas of North America. And average chemistry is very difficult to rationalize, the one shown here may not be similar to your native material.
Pumicite is easily processed and quite fine in nature.
Volcanic ash materials vary widely in their chemistry, it is impossible to formulate a representative analysis. Some can be used in amounts to 50% or more of the glaze batch but most require the addition of fluxes, kaolin to form a good glaze.
Example formulas for two well known materials:
St. Helen's
Ca0 6.8%
Mg0 6.1
K20 .5
Na20 3.9
Fe203 6.8
Mn0 .2
Ti02 .3
P205 .2
Al203 22.32
Si02 51.85
Pinatubo
Ca0 5.6%
Mg0 2.7
K20 1.6
Na20 4.4
Fe203 5.6
Ti02 .8
Al203 16.1
Si02 61.9
Linked Articles
Formulating Ash and Native-Material Glazes
How to have a volcanic ash analysed and them use ceramic chemistry to create a glaze that contains the maximum possible amount of the ash for the desired effectVolcanic Ash
Joseph Herbert overviews the technical and practical aspects of this interesting group of materials
URLs
- Volcanic ash beds of North Dakota - http://www.ndsu.nodak.edu/instruct/schwert/ndgs/nd_ash.htm
Authors
- Tony Hansen (Owner)
XML
<?xml version="1.0" encoding="UTF-8"?>
<material name="Volcanic Ash" descrip="" generic="1" rawmineral="0" searchkey="Pumicite" loi="0.00">
<families>
<family name="Flux Source"/>
</families>
<regions>
<region name="North America"/>
</regions>
<oxides>
<oxide symbol="CaO" name="Calcium Oxide, Calcia" status="U" percent="6.000" tolerance=""/>
<oxide symbol="MgO" name="Magnesium Oxide, Magnesia" status="U" percent="3.000" tolerance=""/>
<oxide symbol="K2O" name="Potassium Oxide" status="U" percent="1.000" tolerance=""/>
<oxide symbol="Na2O" name="Sodium Oxide, Soda" status="U" percent="4.000" tolerance=""/>
<oxide symbol="TiO2" name="Titanium Dioxide, Titania" status="" percent="0.500" tolerance=""/>
<oxide symbol="Al2O3" name="Aluminum Oxide, Alumina" status="" percent="15.000" tolerance=""/>
<oxide symbol="SiO2" name="Silicon Dioxide, Silica" status="" percent="67.000" tolerance=""/>
<oxide symbol="Fe2O3" name="Iron Oxide, Ferric Oxide" status="" percent="2.000" tolerance=""/>
</oxides>
<volatiles>
<volatile symbol="" name="" percent="1.000" tolerance=""/>
</volatiles>
<references>
<reference name="seealso" reason=""/>
</references>
<notes>
<note>Pumicite is composed of minute particles of volcanic glass. Deposits resulted from volcanic eruption blowing large quantities of material into the air which settled in layers, sometimes in thicknesses which compressed to 30 feet or more. Volcanic ash particles are non-crystalline due to the quick cooling during formation. This material thus takes on the unique melting properties associated with a glass.
The chemistry is similar to granite or ryolite. Raw color varies and deposits can be found over wide areas of the central and western areas of North America. And average chemistry is very difficult to rationalize, the one shown here may not be similar to your native material.
Pumicite is easily processed and quite fine in nature.
Volcanic ash materials vary widely in their chemistry, it is impossible to formulate a representative analysis. Some can be used in amounts to 50% or more of the glaze batch but most require the addition of fluxes, kaolin to form a good glaze.
Example formulas for two well known materials:
St. Helen\'s
Ca0 6.8%
Mg0 6.1
K20 .5
Na20 3.9
Fe203 6.8
Mn0 .2
Ti02 .3
P205 .2
Al203 22.32
Si02 51.85
Pinatubo
Ca0 5.6%
Mg0 2.7
K20 1.6
Na20 4.4
Fe203 5.6
Ti02 .8
Al203 16.1
Si02 61.9</note>
</notes>
</material>
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