Carved Volcanic Rock Foot Stool. Four feet with a curved middle. 

Size: 12 1/2 x 11 x 6 in. 

#4691 . 

Volcanic rocks are formed from lava erupted from a volcano. In nature volcanic rocks grade into hypabyssal and metamorphic rocks and constitute an important element of some sediments and sedimentary rocks. Volcanic rocks and sediment that form from magma erupted into the air are called “pyroclastics,” and these are also technically sedimentary rocks. It has been estimated that volcanic rocks cover about 8% of the Earth’s current land surface, with an inestimable amount on the ocean floor where volcanic activity is most prevalent. One of the most unique and versatile of all volcanic rocks is pumice, widely used to make lightweight concrete and insulative low-density cinder blocks. The air-filled vesicles in this porous rock serve as a good insulator, and was used as far back as Roman times to build the huge dome of the Pantheon as well as an additive in cement for most of their aqueducts. Ancient civilizations in South and Central America used it to build furniture that was light enough to move with ease but sturdy enough to support significant weight, and pumice was used by ancient Pacific Islanders as ballast on their long journeys. Throughout history legends of “floating islands” that sometimes disappeared shortly after being discovered were dismissed by conventional academia, until scientists discovered in the 19th Century that enormous areas of pumice habitually formed on the surface of oceans, with one of the largest ever encountered found in 2012, being roughly 10,000 square miles in size.