👉 Billitonite is a mineral that is commonly found in the Earth's crust. It is a type of quartz and is composed of two layers of quartz, with one layer being more dense than the other. This means that it has a higher density at the surface compared to the denser layer below. The minerals within this material are primarily quartz and feldspar (a group of minerals that include hornblende, spinel, and mica). Billitonite is typically found in the upper
