✡ Pyrite is formed in hydrothermal veins, sedimentary rocks, and metamorphic rocks. It requires iron, sulfur, and certain environmental conditions for its formation. Bacterial action can also contribute to its formation in sedimentary rocks.
✡ Selenite is formed in igneous and metamorphic rocks through a process called adularization, where layers of feldspar minerals align to create its unique shimmering effect. Found in granites, pegmatites, and syenites, it develops under specific conditions of heat and pressure, making it a rare and mesmerizing gemstone.