Common in Arizona.
Chemical Formula: Fe3Al2(SiO4)3
Specific Gravity: 4.05
Almandine is a garnet group mineral. It is a common variety of garnet and is known for its deep red to reddish-brown color. The name “almandine” is derived from “alabanda,” an ancient city in Asia Minor, where the mineral was historically found. Almandine’s color is due to the presence of iron in its crystal structure.
Almandine crystals are often cubic, typically as dodecahedrons or trapezohedrons. They can be found in various types of rocks, including metamorphic and igneous rocks. Almandine garnets are often found in schists, gneisses, and certain types of granites.
One of the noteworthy features of almandine is its use as a gemstone. While not as well-known as some other red gemstones like rubies, almandine can be cut and polished to create attractive gemstones. These gemstones are often referred to as “almandine garnets” and can exhibit a deep red color that ranges from a brownish-red to a purplish-red hue.
In geological terms, the presence of almandine garnets in rocks can provide information about the conditions under which the rocks formed. The mineral’s resistance to weathering and erosion also makes it a common component in heavy mineral sands and placers, where it can be concentrated along with other durable minerals.