krüptokristalliline

Kryptokristalliline refers to a rock texture where the individual mineral crystals are so small that they are not visible to the naked eye. These crystals are typically microscopic, requiring magnification, such as from a microscope or an electron microscope, to be identified and studied. Rocks exhibiting a cryptocrystalline texture are often characterized by their fine-grained appearance.

This texture is common in igneous rocks, particularly volcanic rocks that cooled rapidly. The quick cooling process prevented larger crystals from forming, resulting in a mass of very small crystals or even a glassy, amorphous structure. Examples of cryptocrystalline igneous rocks include some types of basalt, rhyolite, and obsidian, though obsidian is technically amorphous glass rather than crystalline.

Sedimentary rocks can also display cryptocrystalline textures. This often occurs when minerals precipitate directly from water, forming very fine particles that accumulate. Chert, a type of sedimentary rock composed primarily of microcrystalline or cryptocrystalline quartz, is a prime example. The smooth, conchoidal fracture often seen in chert is a characteristic of its fine-grained, cryptocrystalline nature. The term "cryptocrystalline" literally means "hidden crystal," highlighting the microscopic scale of the mineral grains.