Assaying, a process for determining the amount of a certain metal contained in an ore or alloy. See more »

Dust, fine particles of earth or other matter capable of being carried by currents of air. See more »

Geophysics, the application of the science of physics to the study of the earth. See more »

Glacial Period, or Ice Age, a time when continental glaciers, resembling those now on Greenland and Antarctica, covered almost a third of the world's land surface. See more »

Polymer crystals are amazing in that they can absorb many times their size. In fact, one pound of these crystal flakes can hold up to 50 gallons of water. Find out what these polymer crystals are and why they are able to absorb so much water. See more »

Ice, frozen water. (Dry ice is not frozen water, but carbon dioxide in solid form) Under ordinary conditions, water changes to ice at 32 F. See more »

Radioactive Dating, the calculation of a substance's age by measurement of the radioactive material it contains or of the amount of natural atomic fission that has occurred in the substance. See more »

Water, the most common substance on Earth's surface. It also covers more than 70 percent of Earth's surface area and exists as vapor in Earth's atmosphere. See more »

My fiancee gave me a 1 carat diamond in my engagement ring. What is a carat? And how does it relate to a karat, as in "18 karat gold"? See more »

Water wells are a common source of water for many people. Learn about some of the different types of water wells in this article. See more »