GEOLOGY

Detailed explanation-1: -Geodes contain hollow spaces called vugs. Vugs range in size from a few millimeters to crystal caves.

Detailed explanation-2: -geode, hollow mineral body found in limestones and some shales. The common form is a slightly flattened globe ranging in diameter from 2.5 to more than 30 cm (1 to 12 inches) and containing a chalcedony layer surrounding an inner lining of crystals.

Detailed explanation-3: -A geode is a hollow rock lined with an inside layer of sparkling crystals. On the outside, geodes appear nondescript and are easily overlooked. However, cracking open a geode will display an array of colorful crystals.

Detailed explanation-4: -Igneous rocks are formed from molten rock called magma. They are mostly crystalline (made up of interlocking crystals) and usually very hard to break.