Definition of "feldspar" [feld•spar]

• Any of a group of abundant rock-forming minerals occurring principally in igneous, plutonic, and some metamorphic rocks, and consisting of silicates of aluminum with potassium, sodium, calcium, and, rarely, barium. About 60 percent of the earth's outer crust is composed of feldspar. (noun)

American Heritage(R) Dictionary of the English Language, Fifth Edition. Copyright (c) 2011 by Houghton Mifflin Harcourt Publishing Company. Published by Houghton Mifflin Harcourt Publishing Company. All rights reserved.

• "The name feldspar is a contraction of the longer name fieldspar, as some early specimens were found in fields."
• "Sand, the proppant, primarily quartz and feldspar aka ground up rock, is the material that gets lodged in cracks that open up, and keep those cracks open when force and pressure are removed, allowing less resistance between underground hydrocarbons, to allow them to become newly liberated hydrocarbons, which we use to power a significant portion of our country."
• "(Common orthoclase feldspar, which is frequently of a brownish pink or flesh color, will do.)"