Final answer:
Tremolite is a double-chain silicate mineral in the amphibole group, indicative of high-pressure metamorphic conditions and found in subduction zones.
Step-by-step explanation:
Tremolite is a member of the amphibole group of silicate minerals with the chemical formula Ca₂Mg₅Si₈O₂₂(OH)ₓ. It is part of a double-chain silicate structure, which is one of the several ways that silicate tetrahedra can link together. These chains form as silica tetrahedra share oxygen atoms, creating a repeating pattern that contributes to the formation of silicate minerals found throughout the Earth's crust.
Amphiboles like tremolite have silicate chains that are arranged in a double-chain structure, unlike single-chain silicates (e.g., pyroxenes) or framework silicates (e.g., feldspars). Furthermore, tremolite often forms during the metamorphism of ultramafic rocks and is associated with high-pressure, low-temperature conditions typically found in subduction zones. As such, tremolite can be a useful mineral for geologists when determining the pressure-temperature history of metamorphic rocks.