Cryptocrystalline
Cryptocrystalline refers to a type of mineral structure that is composed of microscopic crystals that are too small to be seen with the naked eye. This results in a smooth, uniform appearance without visible grain or individual crystals. Cryptocrystalline minerals are typically translucent to opaque and have a waxy or greasy luster. Examples of cryptocrystalline minerals include chalcedony, agate, and jasper.