👉 A beerbachite is a type of mineral that occurs in the Earth's crust. It is composed of two minerals, namely biotite and lebdaite (also known as beryl), which are both found within the Earth's mantle. Beerbachites are primarily found in the uppermost part of the Earth's crust, between 100-500 kilometers deep. The mineral composition of beerbachite varies depending on its depth, with biotite being more prevalent