Tourmaline is one of the most chemically complicated of all Silicate minerals. It is a complex Silicate of Aluminum and Boron and the composition varies widely with Sodium, Calcium, Iron, Magnesium, Lithium and many other elements that enter into it’s structure. It can occur in a long, slender needle-like crystal to a thick prismatic and columnar crystal to a radial like daisy formation. It comes in many colors usually black and brown (iron rich); brown and yellow (magnesium rich); and blue, red, green, yellow, and pink (lithium rich). This mineral is found in igneous rocks, like Granite Pegmatite, and metamorphic rocks such as Schist and Marble.
Feldspars are a group of rock-forming tectosilicate group of minerals containing potassium, sodium, calcium and aluminium silicatesminerals that make up as much as 60% of the Earth’s crust. They are the most common rock-forming minerals. Feldspars crystallize from magma as veins in both intrusive and extrusive igneous rocks and are also present in many types of metamorphic rock. Feldspars are also found in many types of sedimentary rock.