Mt. St. Helens Ash

Alternate Names: Mount Saint Helen\'s Ash

Oxide	Analysis	Formula
SiO2	62.51%	4.42
Al2O3	17.48%	0.73
TiO2	0.59%	0.03
Fe2O3	5.36%	0.14
MgO	2.43%	0.26
MnO	0.08%	-
CaO	5.08%	0.38
Na2O	4.33%	0.30
K2O	1.38%	0.06
LOI	0.75%	n/a
Oxide Weight		421.69
Formula Weight		424.88

Notes

Mount St. Helens Ash is available by the grace of the eruption of the above mentioned mountain in Washington State USA about 1980. Large areas of the state were blanketed by a layer of the ash that people had to clear with shovels like snow.

It has been speculated that P₂O₅, which shows up in some other analyses that have been done, is responsible for the typical "skin" of color that appears over the body of the glaze.

Atomic Absorption Analysis results 6/9/80
DR Pevear, Dept of Geology, West Washington Univ., Bellingham, WA

1 2 3 4 5 6 7 8 9
SiO₂ 61.90 66.05 60.81 64.54 62.99 63.46 64.20 65.78 63.92
Al₂O₃ 19.43 18.46 19.69 18.69 17.34 16.62 17.23 16.62 16.31
TiO2 .73 .52 .73 .60 .63 .63 .60 .49 .49
Fe₂O₃ 6.84 4.49 6.97 5.46 5.91 5.57 4.94 4.44 4.59
MgO 3.63 1.78 3.82 2.62 2.74 2.40 1.94 1.69 1.71
MnO .11 .07 .10 .08 .09 .08 .07 .06 .06
CaO 6.05 4.19 6.27 5.56 5.53 5.39 5.12 4.35 4.13
Na₂O 4.36 4.59 4.33 4.49 4.21 4.41 4.60 4.62 4.16
K₂O 1.06 1.65 .97 1.29 1.23 1.43 1.46 1.63 1.94
LOI .28 .80 .50 .20 n.d. .96 .58 .76 2.04

The analysis provided is an average of the above.

1 Yakima, WA
2 Spokane, WA
3 Yakima, WA (S34 T9N R5E)
4 Mt. St. Helen (S34 T9N R5E) USGS
5 Mt. St. Helen USGS
6 Randle, WA
7 Castle Rock, WA
8 Missoula, MT
9 Denver, CO

Related Information

Links

Articles	Volcanic Ash Joseph Herbert overviews the technical and practical aspects of this interesting group of materials
Materials	Navajo Pumice
Materials	Volcanic Ash Powdered volcanic ash is used to make ceramic glazes, some varieties have a chemistry similar enough to glaze that high percentages can be employed.
Materials	Mount Pinatubo Ash
Typecodes	Flux Source Materials that source Na2O, K2O, Li2O, CaO, MgO and other fluxes but are not feldspars or frits. Remember that materials can be flux sources but also perform many other roles. For example, talc is a flux in high temperature glazes, but a matting agent in low temperatures ones. It can also be a flux, a filler and an expansion increaser in bodies.

By Tony Hansen
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