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Volcanic Ash

Alternate Names: Pumicite

Oxide Weight383.98
Formula Weight387.86
If this formula is not unified correctly please contact us.

Pumicite is composed of minute particles of volcanic glass. Pumicite is easily processed due to its fine in nature. 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. Volcanic ash materials vary widely in their chemistry, it is impossible to formulate a representative analysis, the one shown here may not be similar to your native material.

Some types of volcanic ash are balanced enough chemically that they can be used in amounts to 50% or more of the glaze batch. Most require the addition of fluxes and kaolin to form a glaze with reasonable firing and suspension properties.

More sample formulas of two well known materials:


Ca0 5.6%
Mg0 2.7
K20 1.6
Na20 4.4
Fe203 5.6
Ti02 .8
Al203 16.1
Si02 61.9

Out Bound Links

In Bound Links

By Tony Hansen

XML for Import into INSIGHT

<?xml version="1.0" encoding="UTF-8"?> <material name="Volcanic Ash" descrip="" searchkey="Pumicite" loi="0.00" casnumber=""> <oxides> <oxide symbol="CaO" name="Calcium Oxide, Calcia" status="" percent="6.000" tolerance=""/> <oxide symbol="MgO" name="Magnesium Oxide, Magnesia" status="" percent="3.000" tolerance=""/> <oxide symbol="K2O" name="Potassium Oxide" status="" percent="1.000" tolerance=""/> <oxide symbol="Na2O" name="Sodium Oxide, Soda" status="" 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="LOI" name="Loss on Ignition" percent="1.000" tolerance=""/> </volatiles> </material>

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