Precious Beads Dolomite

Crystals of precious beads dolomite from the Midwest USA are well known for their beautiful pink color, pearly luster, and unusual crystal habit. It comes from the carbonates class and trigonal crystal system. Colorless precious beads dolomite is rarely faceted because of its softness and perfect cleavage, although some crystals are cut for collectors-usually in a step cut. Precious beads dolomite is composed by calcium magnesium carbonate. The luster is vitreous to pearly and the fracture is subconchoidal.

With refractive index range between 1.502-1.681 and specific gravity between 2.8-2.9, precious beads dolomite comprises the chief source of magnesium acquired from the crust of the earth. The hardness is stopped at 3.5-4 and the dispersion is 0.027. It is a sedimentary rock-forming mineral, and is usually mined from massive beds that can reach several hundred feet in depth. This brittle stone consists of calcium magnesium carbonate. Precious beads dolomite has a 0.179 birefringence and a perfect-in-three-directions cleavage.

Precious beads dolomite was first described in 1797 by French naturalist and geologist Deodat de Gratet de Dolomieu (1750-1801), from its occurrence in a region of the Italian Alps (now called the dolomites in his honor). Precious beads dolomite can be several different colors, but colorless and white are most common. In less number, there is also gray to pink too. The luster of precious beads dolomite is probably one of the best examples of a pearly luster. The sources of precious beads dolomite are in Mexico, Midwest USA, Spain, Switzerland, and Canada (Ontario).

Pure precious beads dolomite may appear either white or yellow natural gemstones. The habit is rhombohedra and saddle-shaped intergrowths. Small amounts of iron in the composition give the crystals a yellow to brown tint, a high manganese content can make the crystals a pale rose-pink, and cobalts turns it a more purplish pink. Precious beads dolomite looks very much like calchite, which consists only of calcium carbonate. It forms white, gray to pink, and mainly curved crystals, although the habit is normally massive. Its physical properties are similar to those of calcite.

Crystal Stone Chrysoprase

The name crystal stone chrysoprase comes from the Greek chyros, meaning “golden,” and prason, “leek,” which describes the color of the stone. Across the years, this name was applied to several yellowish green gemstones, including beryl, but eventually it became limited to the apple-green, microcrystalline variety of chalcedony. Crystal stone chrysoprase comes from the class of framework silicates with trigonal crystal system. It is composed by silicon dioxide. The hardness is stopped at level 6.5. Crystal stone chrysoprase has vitreous to resinous luster and conchoidal fracture. The duller, leek-green stones have been called prase instead. The habit is massive, or as veins in rock. Crystal stone chrysoprase is found mostly in Australia, although it has been found in Brazil and the Ural Mountains in Russia and in Austria.

Crystal stone chrysoprase is usually translucent, but poorer quality stones may appear opaque. A small number of crystal stone chrysoprases are semitransparent and even transparent. It has none cleavage. If the color is good, these stones fetch a high price. Crystal stone chrysoprase is usually fashioned into cabochons, beads, and bangles, or it is carved to create jewelry and other ornamental objects. It is easily worked and takes a fine polish. The highest-quality material is a rich, evenly colored apple green, and does not contain any flaws, inclusions, or imperfections. Common colors are pale green, yellowish green, and deep green. Crystal stone chrysoprase is among the most valuable of the chalcedonies. The dispersion is 0.013 and the specific gravity is in between 2.57-2.64.

Crystal stone chrysoprase is cryptocrystalline, that is, it has a microscopic crystalline structure. Under high magnification, these crystals look like parallel fibers. The refractive index of crystal stone chrysoprase is 1.530-1.538 and the birefringence is up to 0.004. Unlike most other green stones, which derive their color from chromium or vanadium, crystal stone chrysoprase’s distinctive green color is the result of included oxidized nickel compounds, such as nickel silicate clay minerals. A rare, related chalcedony in darker, more vibrant shades of green is colored by chromium, it occurs in Zimbabwe and is called mtorolite, but is sometimes sold as “chrome chalcedony”, one of the quite antique natural gemstones.