Minerals, Metals, and Other Materials
Rocks and Minerals
How does a rock differ from a mineral?
Mineralogists use the term “mineral” for a substance that has all four of the following features: it must be found in nature; it must be made up of substances that were never alive (organic); it has the same chemical makeup wherever it is found; and its atoms are arranged in a regular pattern to form solid crystals.
Although “rocks” are sometimes described as an aggregate or combination of one or more minerals, geologists extend the definition to include clay, loose sand, and certain limestones.
From what type of stone was Mount Rushmore National Memorial carved?
Granite. The monument, in the Black Hills of southwestern South Dakota, depicts the 60-foot-high (18-meter-high) faces of four United States presidents: George Washington (1732–1799), Thomas Jefferson (1743–1826), Abraham Lincoln (1809–1865), and Theodore Roosevelt (1858–1919). Sculptor Gutzon Borglum (1867–1941) designed the monument, but died before the completion of the project; his son, Lincoln, finished it. From 1927 to 1941, 360 people, mostly construction workers, drillers, and miners, “carved” the figures using dynamite.