Garnet Occurrence Garnet is found in a wide variety of metamoprhic rocks and in some igneous rocks. Compositon Garnet is typically a solid solution of a number of end members, including almandine (Fe3Al2Si3O12), pyrope (Mg3Al2Si3O12), spessartine (Mn3Al2Si3O12), grossular (Ca3Al2Si3O12), and andradite (Ca3Fe2Si3O12). Identification Garnet is one of the few common isotropic minerals. It is generally colorless or has a pale tinge, often irregularly fractured, and has high relief. Important properties  ·Appearance and habit - Euhedral crystals may have 6 or 8 sides. More typically garnet is subhedral equant or anhedral.  ·Color - generally colorless, but sometimes has a slight pinkish or grayish tinge  ·Inclusions - inclusions of quartz and other minerals are common Similar minerals:  ·Spinel, also isotropic, may occasionally be confused with garnet, but spinel usually is strongly colored while garnet is not.  ·Perovskite resembles garnet but has much higher relief.

Cordierite and Garnet from Kazabazua, Quebec Garnet is one of the few common isotropic minerals, and the appearance of the large garnet in these photos is typical. Garnet is generally characterized by irregular fractures, high relief, and it often contains inclusions of other minerals. Besides garnet, these views show large twinned cordierite (left side) and some quartz inclusions in the garnet. Minor brown biotite and other quartz grains (not inclusions) are also present. The cordierite interference colors and twins, visible in the XP view, make this cordierite appear similar to some plagioclase. The garnet is isotropic and so is black in the XP view. The field of view is 2.5 mm across.

Euhedral Garnet in a Muscovite Schist from near Poughkeepsie, New York This thin section contains a sea of fine grained muscovite (with some minor graphite) that includes two large garnets. The garnets are euhedral, typcial of low- to medium-grade metamorphic rocks such as this one. The minor opaque mineral is graphite. The field of view is 3.5 mm across.

Garnet and Chloritoid in a Muscovite Schist from near Poughkeepsie, New York These views show fine-grained muscovite intermixed with some minor graphite, a large euhdral garnet (black in the XP view), a blade of chloritoid (twinned and showing good cleavage and gray interference color in the XP view). A small flake of biotite is between the garnet and the chloritoid. The fractured garnet contains two flakes of graphite, visible in the PP view. The field of view is 3.5 mm across.

Garnet, Paragonite and Chlorite The photos show a large garnet (high relief, isotropic) near the center of the photograph. Most of the material to the left of the garnet is paragonite (high order interference colors, XP), a white mica often indistinguishable from muscovite without chemical analysis. Some flakes of chlorite can be seen within and to the right of the garnet. The chlorite has lower relief than the garnet and shows gray interference colors (XP). Quartz, graphite, and minor biotite are also present. This sample comes from woutheastern Vermont. The field of view is about 3 mm across.

Garnet Schist from Western Massachusetts Most of this view is garnet (clear, PP; istropic, XP). it contains inclusions of quartz and ilmenite (opaque) and is surrounded by quartz and some grains of brown biotite. Additionally, there are some very small grains of sillimanite below and above the garnet (high relief, PP) but they are difficult to pick out at this scale. The field of view is about 2.5 mm.