Moonstone, a moderately hard, transparent or translucent gemstone with a pearly or milky luster. Moonstone is a feldspar, either orthoclase (potassium aluminum silicate) or albite (sodium aluminum silicate). The stone is found in all continents except Africa; the best specimens are mined in Sri Lanka. It is the birthstone for June and represents health.
Comets are remarkable pieces of our universe's past, and they tell us a great deal about how the universe was formed. Learn about the long but rewarding process of discovering and analyzing comets.
The Smithsonian Institution began with an unexpected donation and has now grown to a massive collection of American artifacts. The Smithsonian is world renowned for its museum and for scientific endeavors. Take this quiz and learn more about the famous Smithsonian Institution.