Virginia State Gemstone
Amazonite, also called Amazon stone, is a yellow-green to bright verdigris to greenish-blue variety of potassium feldspar and a gemstone-quality microcline. Microclines are minerals of the feldspar group that are used to make enamel, porcelain, and glass. Amazonite’s color is distributed irregularly across the stone, and some specimens display fine white streaks. The color is caused by high levels of lead and water.
Although Virginia does not have an official state gemstone, amazonite represents the state well. Amazonite from Amelia County, Virginia, sets the world standard for quality.
Although no amazonite deposits have been found in Brazil’s Amazon River area, this mineral is indeed named for that region. Amazonite occurs elsewhere in Brazil, however. The name may also come from the shades of green that occur in the Amazon rainforest, from green stones that have been found in the Amazon River area, or from the Amazons themselves. A Brazilian legend tells that the legendary female warriors of the Bronze Age, the Amazons, gave green stones to their male visitors. These stones were believed to be amazonite, but were probably nephrite jade. (Fine amazonite can be mistaken for jade.)
The word microcline comes from the Greek words for "little" and "inclined," for the small deviation of the cleavage planes from 90°.
FORMATION AND OCCURRENCE
This mineral is found in granites and pegmatites. About 250 million years ago, magma pushed up to the earth’s surface, leaving elements in rock fractures that eventually formed the crystals of the pegmatites.
A well-known deposit, perhaps the most important, is Crystal Peak in Teller County, Colorado. At some localities, amazonite occurs with smoky quartz. This combination makes excellent collector specimens.
Although amazonite does not have a detailed history, it is known that humans have appreciated amazonite for centuries. Carved ornamental objects of amazonite have been found in ancient Egypt.
Russia was the most important source for this gem until 1876, when impressive specimens from Colorado were displayed at the Centennial Exhibition. Since then, Colorado has been the world’s most important source of amazonite.
Polishing amazonite brings out its bright green color. It therefore makes a fine gemstone. However, since it is opaque to translucent, it is not faceted. Its relative softness, 6 to 6.5 on Mohs scale, means it is scratched fairly easily, and therefore not suitable for rings. High-quality amazonite is used for cabochons, beads, carvings, and spheres. The stone makes fine earrings, pendants, and brooches. Although somewhat rare, amazonite is not an expensive gem. The most sought-after stones are saturated green with even color distribution.
Since amazonite is suitable for polishing and carving, it is a popular mineral specimen for collectors. Microclines may be used in the manufacture of glass, enamel, and porcelain.
This stone is said to calm and soothe. It is also believed that amazonite can enhance creativity and self-expression, and can boost self-confidence. The gemstone is even believed to possess the power to make married life better.
Chemical Formula: KAlSi3O8
Crystal Structure: Triclinic
Hardness (Mohs): 6+
Color: White, cream, light yellow, light brown, reddish-brown, pink, blue-green, deep green
Transparency: Translucent to opaque
Refractive Index: 1.522-1.530
Cleavage: 2,1 - basal ; 2,1 - prismatic ; 3,1 - pinacoidal. The cleavage angle is about 90º
Fracture: Conchoidal to uneven
Some data courtesy of the Mineralogical Society of America
Author: World Trade Press