The chemical formula of mineral Aegirine is indicated by NaFe(Si)2(O)6 or Sodium Iron Silicate. Aegirine is actually a Silicate mineral. this mineral is also sometimes called Acmite. This mineral is known as a member of the amphibole group with small maximum extinction angle and negative elongation when evaluated between crossed nicols of petrographic polarizing light microscope. The name Aegirine is of Greek origin. The alternate name Acmite was derived from a Greek word akme, meaning point. This is relative to the crystal shape of the mineral. The name Aegirine however, was derived from the name of a Teutonic or Scandinavian god of the sea, Aegir. The name Aegirine was given when the first specimens of this mineral were discovered in Norway.
Aegirine is known to crystallize in the monoclinic system of crystal formation. In optical mineralogy, the monoclinic system of crystal formation comprises crystals having three axes of unequal lengths. Two of which are usually found in a position that is oblique or not perpendicular to one another. However, both of which are commonly found perpendicular to the third axis. The crystal formation of this mineral is of classic impression among collectors because it commonly exhibits nice and fascinating images under polarizing light microscopes. Aegirine mineral forms crystal structures appearing to be steep, inclined pyramid sitting on top of prismatic crystals. A majestic view under a geological polarizing microscope as exhibited by its tall, monument-like crystals that are usually opaque in appearance, as they pop out splendidly from their host rocks.
Aegirine exhibits a variety of splendid colors when viewed with the aid of polarizing light microscopes used in optical mineralogy. The colors shown may vary from black to greenish and sometimes brownish black when evaluated under petrographic polarizing light microscopes. It commonly occurs in green or brown color that can appear more splendidly exhibited when viewed under polarized light microscope for mineralogists. A pleochroism from green to yellow green or from brown to greenish yellow can be seen clearly exhibited by Aegirine when it is viewed with the aid of petrographic polarizing microscope. Aegirine can be also be found with long prismatic crystal inclusion when closely viewed with the aid of petrographic polarizing light microscope used in optical mineralogy. The visibility of some steep-asymmetrical pyramid terminations is also more clearly exhibited when the specimens are viewed under polarizing light microscopes for geologists. Sometimes they may appear compact and fibrous, striated, or may be of disseminated grains, all of which are very interesting when viewed under polarized microscopes used in optical mineralogy. It can be also found showing a splendid needle-like crystals appearance when evaluated under polarizing microscope for mineralogists.
Aegirine is most commonly found showing a vitreous to resinous luster when viewed in reflected light of a polarizing microscope for mineralogists. The fracture formed when the mineral is examined under several adjustments on the aperture diaphragm of the polarized light microscope is usually uneven and sometimes crystals are considered brittle, a property commonly displayed by most non-metallic minerals. The cleavage found is most commonly perfect in two directions at near 90 degree angle when viewed under a petrographic polarizing microscope. The specific gravity of mineral Aegirine is approximately 3.5 grams per cubic centimeters to 3.6 grams per cubic centimeters, which is considered above average for translucent minerals. The hardness measure of mineral Aegirine when it is evaluated using the Mohs scale method is usually found ranging from 6 to 6.5 giving an average of 6.25. Aegirine is most commonly found leaving a white and sometimes gray streak when mineral specimen is rubbed on a white porcelain streak plate.
Aegirine is most commonly found displaying high surface relief when viewed under several adjustments on the aperture diaphragm of the petrographic polarizing microscope. Aegirine also shows very strong birefringence when evaluated in plane-polarized light of petrographic polarizing light microscope. Aegirine is usually found having a biaxial negative figure with a rather large axial angle when viewed between crossed nicols of polarizing light microscope for geologists. when viewed under geological polarizing microscope used in optical mineralogy, Aegirine is usually found exhibiting a variety of interference colors. Mineral Aegirine is considered as a rather rare mineral. These kinds of mineral commonly occur in contact metamorphics. Sometimes they are also formed in Alkali Nepheline Syenites and other similar igneous rocks.
