Tides are the rise and fall of sea level that is caused by the gravitational pull of the moon and the sun on the Earth. Waves are actually energy that moves across the surface of the water. In the scientific...

Geology is the scientific study of solid Earth, though it can also refer to any other celestial body, the rocks of which it is composed, and the processes by which they evolve. It includes studying both the...

Gemstones are rare pieces of minerals that are found in the ground, which are then cut and polished to be used in jewelry and other decorative pieces. Crystals are pure substances whose atoms, molecules, or...

Crystals are pure substances whose atoms, molecules, or ions are arranged in an ordered pattern, where they extend in all three spatial dimensions. Minerals are homogenous solids that have regular structures...

Brass is a metal alloy of copper and zinc. Bronze is an alloy of copper and tin.