Pumice Bonsai Grow Media

Pumice is abundant and found in many parts of the world, but not all pumice is created equal. Rūtsu™ pumice media comes from a pumice deposit located in southeast Idaho on the shoreline of an ancient lake known as Lake Bonneville...a vast, freshwater lake that once covered much of North America’s Great Basin region (most of Utah and parts of Idaho and Nevada). The Great Salt Lake is all that remains of Lake Bonneville. The volcano that produced the pumice is about a mile to the north of the mine. The volcanic ash (pumice) was deposited in the lake, where it was washed and stratified over centuries. The relentless wave process cleaned the pumice of the undesirable heavy minerals that are often found in other pumice deposits.

Pumice is not scoria. Scoria is common lava rock, typically red, red/brown, sometimes black, and is often used as a decorative landscaping ground cover. Scoria forms from basaltic magmas, while pumice is of rhyolitic magma origin. The difference is important. Pumice has many more vesicles—trapped bubbles—than scoria and the walls between them are very thin. Pumice is essentially a foamed glass stone, amorphous (non-crystalline) in structure. The pumice from our deposit is neutral in pH, and more tightly structured (dense) than is typical—it (for the most part) does not float.