Bentonite, the name given to a group of industrially useful clays containing the mineral montmorillonite. Bentonite clays are primarily aluminum silicates, mixed with varying amounts of sodium, calcium, or magnesium. A major use of bentonite clays is in oil-well drilling mud, a mixture of water, bentonite, and chemicals used to cool the drilling bit and carry away cuttings from the well. Certain types of bentonite expand to several times their original volume when mixed with water; they are used as sealants in dams and concrete-lined canals.
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.