Pulverized rock is the simplest description for the volcanic ash spewed across Washington by Mount St. Helens, a Battelle Northwest Laboratories scientist said Tuesday.
Environmental chemist Dave Robertson told the National Association of Accountants the mountain's explosive eruption Sunday "literally pulverized" the top 1,500 feet of the cone.
"The ash is mainly feldspar, an aluminum silicate, and silicon dioxide, of which sand is made," Robertson said. "It also contains calcium, magnesium, sodium, ammonia, potassium and various sulphates. If leached with water, it would make a good fertilizer."
"We thought initially the ash would contain hydrogen sulphide, mercury, boron or other very toxic materials like sulfuric acid, but it is not dangerous, " he said. "If it starts erupting lava, we might see a different ash we'd be more concerned about."
Robertson and two other Battelle scientists flew to St. Helens Monday to collect gas samples from the eruption cloud. Battelle is studying the volcano's emissions as part of its geothermal energy research, he said.
Robertson said Mount Adams had changed from pristine white to solid black.
"This will cause severe problems this summer," he said. "The black ash will absorb heat from the sun and melt the snow beneath it. We may see flooding of the Klickitat River."
Color slides taken from the airplane showed new vents opened in the valley floor on the northwest side of St. Helens were throwing ash 1,000 feet into the air.
The airplane was flown through part of the volcanic cloud for 30 seconds to collect gas samples, Robertson said. They were looking for traces of radioactive radon gas, carbon dioxide, and sulfurous gases.
"We were trying to characterize the emissions to determine the environmental effect of geothermal energy," he said. "Hydrogen sulfide gas is the main hindrance to the development of geothermal energy.
Hydrogen sulfide, or "rotten egg" gas is poisonous.
He said the dust's effect on Battelle's airplane prohibits future trips through ash clouds for gas samples.
"The plane's engines ingested so much ash there's a potential of damaging them," he said.