Pumice is natural volcanic glass filled with gas bubbles or fractured into small fragments of jagged glassy foam. It is
the result of molten rock being ejected from the volcano before the rock can recrystallize. Its jagged form makes it a
good candidate for a mild abrasive. It is considered a "mild" abrasive because its hardness is below that of most metals.
Significance in the Environment:
Pumice is isotropic with a refractive index in the range of 1.48 to 1.53. It often contains bubbles or a jagged shape
resulting from the fracturing of surface bubbles of gas. These bubbles are often very elongated as a result of the
explosive ejection of this volcanic glass from the volcano.