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.
Folks in Montana usually expect snow or rain to fall from the sky, not ash. But the 1980 eruption of Mount St. Helens in Washington flung ash across state lines. What is this gritty, gray stuff?
Scientists announced the discovery of the largest known planet in the universe. TrES-4 has a density similar to balsa wood, and some say this gas giant could float on water. Learn why this planet is so puzzling and how planet hunters make amazing discoveries like these.