Feldspar (including electrical insulators, sanitaryware, pottery, tableware, and tile) and other uses, such as fillers, accounted for the remainder. In earth sciences and archaeology, feldspars are used for K-Ar dating, argon-argon dating, and luminescence dating. In October 2012, the Mars Curiosity rover analyzed a rock that turned out to have a high feldspar content. Feldspar Feldspars (KAlSiO – NaAlSiO – CaAlSiO) are a group of rock-forming tectosilicate minerals that make up about 41% of the Earth's continental crust by weight. Feldspars crystallize from magma as veins in both intrusive and extrusive igneous rocks and are also present in many types of
The Menace from Earth The Menace from Earth "The Menace From Earth" is a science fiction short story by American writer Robert A. Heinlein, first published in the August 1957 issue of "The Magazine of Fantasy & Science Fiction". The story is set in the near future, when the Moon is colonized with people living in underground cities. The "menace" of the title is a glamorous woman tourist who visits the Moon colony. She is assigned a young guide named Holly, a 15-year-old girl and aspiring starship designer who is the first-person narrator. Holly's best friend Jeff develops a crush on the "groundhog" visitor,