mafic — an adjective describing a silicate mineral or rock that is rich in magnesium and iron …
magma — a molten rock found beneath the surface of the Earth …
magnesiotaaffeite-2N’2S — species of mineral; faceted specimens exist …
magnesiotaaffeite-6N’3S — species of mineral; data; faceted specimens exist …
magnesite — species of mineral; see magnesite in ‘Classification’ …
magnetite — species of mineral; data; specimens reported (Johnson, McClure, DeGhionno, 1996) …
mahogany obsidian — variety of obsidian; see mahogany obsidian in ‘Classification’ …
malachite — species of mineral; see malachite in ‘Classification’ …
malaia garnet — variety of pyrope-spessartine series; see malaia garnet in ‘Classification’ …
Mali garnet — synonym of grandite; grossular-andradite series …
marble — a rock; see marble in ‘Classification’ …
marialite — species of mineral; see marialite in ‘Classification’ …
marialite-meionite series — a series between marialite and meionite; see marialite-meionite series in ‘Classification’ …
marmatite — variety of sphalerite; opaque, black, Iron-rich …
marquise — a commonly used shape in faceting a gemstone …
melanite — variety of andradite; see melanite in ‘Classification’ …
metamorphic rock — one of the three main rock types; formed from the transformation of igneous or sedimentary rock under the influence of high temperature and pressure …
mica — a group of sheet silicate minerals that includes several closely related materials having close to perfect basal cleavage …
microcline — species of mineral; see microcline in ‘Classification’ …
milky quartz — variety of quartz; see milky quartz in ‘Classification’ …
