👉 Biolite is a type of rock, most commonly found in the Earth's crust. It is made up primarily of calcium carbonate and consists of three layers. The first layer is called the core, which has been solidified by the heat from the earth's mantle. This core contains about 80-90% of the original material. Beneath the core are two layers that are thought to be formed during the early stages of the Earth's history: the upper crust and the lower