Citrine: Citrine is an attractive type of quartz, which is the commonest mineral on the earth's surface. But citrine itself is an uncommon macrocrystalline variety. Its yellow color brought about by its iron hydrate content, its reddish yellow from a trace of ferric iron. It forms hexagonal prisms, terminated by pyramidal shapes. Its faces are often striated, and the crystals twinned and distorted, having (read full)

Indicolite: Indicolite is the blue sodium-rich variety of Tourmaline, and may come in all shades of blue, from light-blue, violet-blue to deep red or deep green. It generally appears quite a deep blue, even the color of dark blue ink, perhaps appearing green in one direction because of its strong pleochroism. Sometimes indicolite is an overall greenish blue, which, unlike the color of greenish blue sapphire, (read full)

Sapphire: Sapphire is the blue variety of Corundum. Sapphires can be a very dark blue, to the point of seeming dense and blackish from a distance, sometimes accompanied by a blue to dull green pleochroism, which is only visible from the side in cut stones. They may also be a strong, but not too bright blue, easily recognizable from a distance, this being the real color. Other possibilities are light, usual (read full)

Enstatite: Enstatite is the most common silicate under the Orthopyroxene group in the larger classification of Pyroxene minerals (which are rock-forming silicates). Orthopyroxenes form a chemical series composed of the magnesium-rich enstatite, and the iron-containing bronzite and hypersthene. It has an orthorhombic crystal system and appears rarely as stubby, prismatic crystals, but more commonly in fibr (read full)

Spinel: Spinel is an extensive group of minerals in which magnesium may be replaced with iron, zinc, and above all, manganese. The hardness and fine colors of gem quality spinel, known as Noble Spinel, set it apart as a gem material from other types of spinel. It normally occurs as distinct octahedral crystals, as clusters also of octahedral habit, or as characteristic twins. The crystals are often iso (read full)

Ruby: Ruby is the most valuable variety of Corundum. The color varies from fiery vermilion to violet red, but because rubies are pleochroic, different colors are also found in the same stone; bright or sometimes brick red in one direction, tending to carmine in the other. The color is also accompanied by marked fluorescence which is stimulated by ordinary, artificial light, and above all, by the ultra (read full)

Morganite: Morganite is a pale red-purple, rose, salmon to purplish red, slightly pink, cesium-bearing variety of Beryl. The Beryl group of silicates includes the important gem varieties emerald, blue aquamarine, pink morganite, and red and yellow beryl. The color of morganite is usually a soft pink without any overtones. It has glassy luster, like other beryls, but its pleochroism is not noticeable. The p (read full)

Kornerupine: Kornerupine is a rare magnesium aluminum borate silicate which occurs as transparent prismatic crystals of the orthorhombic system. It is hard and a has good cleavage in one direction. Colours include a characteristic dark green leaning to brown and a rare and attractive bright vanadium green. This pleochroic colours are brown to greenish brown. Chatoyant stones show a bright eye against a dark g (read full)

Iolite: Iolite is the violet-colored variety of Cordierite (named after French geologist P. Cordier), a silicate of aluminum and magnesium, with an orthorhombic crystal system. Though the name cordierite is used by mineralogists, the name iolite has become established among gemologists. It appears as stubby, prismatic crystals, pesudo-hexagonal twins with a glassy appearance. It is frequently microgranul (read full)

Tugtupite: Tugtupite is a mineral closely related to sodalite and hackmanite, all cyclosilicates whose structural silicate tetrahedrons are arranged in rings. It is also called beryllosodalite and reindeer stone, and crystallizes in the tetragonal system. It is found in fine-grained aggregates of crystals with its own distinctive cyclamen colour. Crystals are very small, tetragonal, almost cubic, or as shor (read full)

Lazulite: Lazulite is a compact, pleochroitic mineral which forms a series to scorzalite. It is dichroic, with a monoclinic crystal system. It appears as pointed, pseudo-dipyramidal, bright blue crystals in microgranular masses. It is hard, medium heavy, fragile with indistinct prismatic cleavage. It is translucent, with vitreous luster. It is infusible, discolors and breaks into small fragments when heat (read full)

Dravite: Dravite also called Brown Tourmaline is a sodium magnesium-rich mineral in the Tourmaline group of silicates, with a hexagonal system. Other members of this group include elbaite (sodium lithium aluminum rich); schorl and buergerite (sodium iron rich); uvite (calcium magnesium rich); and liddicoatite (calcium lithium aluminum rich). A continuous solid solution series exists between uvite and dravi (read full)

Rose Quartz: Rose quartz is a usually cloudy, translucent, delicate pale pink, deep pink, rose-red to quasi-white and often veined variety of Quartz. Also known as pink quartz , rose quartz may occur more often as anhedral masses or rarely as crystals which often reach quite large sizes. Rose quartz almost always occurs in pegmatites in massive crystalline bodies which do not show crystal faces. These larg (read full)

Spodumene: Spodumene is a lithium aluminum silicate that crystallizes in the monoclinic system. It is one of several rock-forming minerals in the Pyroxene group, which are physically-related as their chemical content is quite similar and forms a chain. Fellow pyroxenes are jadeite, enstatite, diopside, hypersthene, augite, acmite, hedenbergite, pigeonite, and aegirineaugite. It appears as prismatic crystals (read full)

Scapolite: Scapolite is a mixed crystal series, a complicated sodium calcium aluminum silicate group composed of calcium-rich meionite, and sodium-rich marialite. It appears as yellow, blue, pink, violet, or colorless prismatic crystals with a tetragonal system, mostly surface-growing, with perfect cleavage. These crystals are usually in aggregates that are massive granular, long columnar, dense, with vitr (read full)

Zoisite: Zoisite is a hydrous calcium aluminum silicate in the Epidote group, with an orthorhombic crystal system, three crystal axes at right angles to each other, all of varying lengths. It appears in elongated, prismatic crystals, with fine parallel lines on the prism faces and usually poorly terminated. It also appears frequently in formless grains, poorly-defined crystals, rodlike aggregates and gran (read full)

Topaz: The transparent, colored crystals, which also have good luster, are widely used as gems.
Topaz is a silicate of aluminum containing fluorine and hydroxyl which occurs in a variety of delicate colors, nicely added by impurities. It is often found in short to long crystal prisms with pyramid-shaped ends, or just clean finished edges. It is often white, semiopaque, milky, or a faded yellow, (read full)

Zircon: Zircon is a zirconium silicate with a tetragonal crystal system, and also contains thorium and uranium. It appears as stubby, prismatic, isolated or sometimes dipyramidal, like two pyramids connected at their bases; or in twins, colorless to yellow, red, brown, gray or green, in irregular granules. It is very hard, heavy, with indistinct cleavage, and shell-like fracture. It is sometimes perfect (read full)