Cryptocrystalline quartz is known as?

Cryptocrystalline quartz is known as chalcedony, which is a type of quartz characterized by its fine, microcrystalline structure. Chalcedony is composed of silicon dioxide (SiO2) and is typically translucent to opaque, displaying a waxy luster. Its structure is made up of extremely small crystals or aggregates of quartz, making it distinct from macroscopic quartz forms.

Chalcedony can take on various colors and is often used in jewelry and decorative items due to its attractive appearance. It encompasses several varieties, including jasper, agate, and onyx. Each of these varieties has specific characteristics that differentiate them. For example, jasper is usually opaque and often exhibits rich colors and patterns, while agate is typically known for its banding and can be both translucent and opaque. Onyx, on the other hand, is a specific type of banded chalcedony distinguished by its dark bands and vibrant colors.

While these other options represent different forms of cryptocrystalline quartz or are closely related to it, the term that specifically refers to the broader group of microcrystalline quartz is chalcedony. This makes it the correct answer in the context of the question.