Rocks & Minerals

An erupting volcano can have significant impact on civilization. Consider the lava flow from the eruption of Mount St. Helens in Washington. Yet, without geological disturbances, lava rock such as...

Mount Etna is Europe's largest and most active volcano. It is characterized by frequent emissions of lava, gas and ash that, in general, pose little danger to the population surrounding its slopes.

Pumice is an igneous rock, which means it is formed from the magma or lava of a volcano. Pumice is full of holes and comes in a variety of colors. A stone of sizable economic worth, pumice can be...

Volcanoes occur at plate boundaries and over hot spots. In each of these situations, magma, which is melted rock within the earth's crust, rises to the surface and exits through a volcanic vent,...

Sixty miles long and 30 miles wide, Mauna Loa is the largest volcano in the world. Mauna Loa is a shield volcano and located on Hawaii's Big Island. It is still active, estimated to erupt every...

Pumice is a unique rock, noted for its light weight and low density (dry pumice can float in water). It is commonly used in cement, concrete and breeze blocks and as an abrasive in polishes,...

The appearance of white "snowflakes" on smooth, black obsidian has fascinated many people. Snowflake obsidian's appearance has caused many people to collect it or use it for metaphysical...

Geodes are spheroid-shaped, hollow rocks that have an inner lining of small crystals projecting inward. Geodes are natural phenomena formed out of millions of years of geological evolution. While...

The stuff that comes out of volcanic explosions is either the molten rock called lava, or by-products of the lava and its intense heat. The Earth's surface is made of floating plates of rock....

The power of nature can really be astounding. It's destructive, dangerous and awe-inspiring. Few things can compare in this way to volcanoes. These enormous sculptures are known for spewing hot...

Basalt, a volcanic igneous rock, occurs worldwide, but especially in India, Scotland, Greenland, Iceland, Canada and the northwestern United States. Most basalt occurs as lava flows, in narrow...

Pumice is a volcanic rock that is formed from lava with a high gas and water content. The lava becomes frothy as the gas escapes, and then becomes light, solidified foam when it cools and hardens....

Sunstones are a variety of feldspar, the most common group of minerals in the crust of the earth. They are formed in molten lava and as the lava wears away, crystals are released, giving the...

Obsidian is a naturally occurring glass formed as igneous rock. It was originally molten lava but cooled so quickly no crystals formed. The lack of crystalline structure means that obsidian in not...