The Stone of Conviction
Aegirine is a lustrous black mineral that is found in a variety of igneous rocks. Its name comes from the Norse god Aegir, who was known for his ability to create large waves. Aegirine is compositionally similar to feldspar and is often used as a substitute for feldspar in ceramic glazes. Aegirine also has a wide range of industrial uses, including the production of abrasives, refractory materials, and welding rod coatings. Aegirine crystals are typically small and stubby, with a pyramidal shape. They are also frequently twinned, meaning that two crystals will grow together in a mirror-like fashion. Aegirine is a relatively soft mineral with a Mohs hardness of 6.5-7.0. It has a vitreous (glass-like) luster and is usually opaque. Aegirine typically occurs as dark green or black prismatic crystals in igneous rocks such as syenite, nepheline syenite, and pegmatite. It can also be found in metamorphic rocks such as gneiss and schist. Aegirine is an essential rock-forming mineral, and geologists often use it to help identify the type of rock in which it occurs.