The geode is recognized. usually , by a spherical configuration which contains a cavity lined with crystalline structure growing toward the center. It is configured in the form of a closed shell, usually containing quartz, amethyst, citrine, or calcite, and partially filled with crystal projecting into the hollow interior; it is separated from the usual limestone or 'mud' matrix by a film of clay. 

The geode structure itself exhibits several properties in addition to the properties of the contained minerals. These properties include facilitation of astral travel, and assistance in the pursuits of mathematics.