Can You Identify This Rock? - Amazonite

Amazonite

Amazonite refers to a species of microcline feldspar that occurs with a blue-green to light green color. The closest resemblance is to turquoise at a glance, but you’re unlikely to confuse the two unless you’re just looking at pictures.

Amazonite is actually named after the Amazon river in South America, called after stones found in the pounding waters. Oddly enough, no one is quite sure if the green stones that give amazonite its name were amazonite, but the name has stuck.

In an even odder turn of events, usage of amazonite as a decorative element dates back to Ancient Egypt… but it seems no one bothered to record anything about it! It wasn’t even recognized as its own species of mineral until the 18th century.

Amazonite’s coloration is different than the majority of blue stones: coloration is dependent on lead and water content in the stone. The lead is tightly bound, you don’t need to take any extra precautions working with it over the normal measures to avoid silica exposure (ie: respirator, work stone wet).

Strictly speaking, amazonite is high-quality microcline but in practice, the term has come to be used for all of it. Microcline often contains numerous internal fractures, so high-grade material is needed for lapidary use.

This pale turquoise material is very popular in both cut and native forms. The large crystals formed by microcline are unique and attractive, while the cut material makes a suitable turquoise replacement in traditional silver jewelry without commanding the high prices that the current turquoise market demands.

Amazonite Physical Features

Classification: Feldspar mineral

Chemical Composition: KAlSi₃O₈ (potassium aluminum silicate)

Color: Typically ranges from green to blue-green, often with a mottled or striped appearance

Streak: White

Hardness: 6-6.5 on the Mohs scale

Cleavage: Perfect in two directions forming nearly right angles

Fracture: Uneven to conchoidal

Luster: Vitreous to pearly on cleavage surfaces

Transparency: Translucent to opaque

Crystal System: Triclinic

Formation and Geology: Amazonite is a type of microcline feldspar that forms in granite and pegmatites. It is often found associated with quartz and other feldspar minerals, and its distinctive color is likely due to trace amounts of lead and water in its composition. The presence of these impurities alters the typical coloration of feldspar from red or pink to the characteristic green or blue-green of amazonite.

Physical Properties: Amazonite is distinguished by its beautiful turquoise to blue-green color, which makes it a popular gemstone. It typically exhibits a grid-like, white streaked pattern due to cleavage and inclusions, adding to its decorative appeal.

Identification Tips:

Color and Appearance: The vibrant green to blue-green color is a key identifier, often accompanied by white streaks or a mottled pattern.
Cleavage: Exhibits perfect cleavage in two directions, which can be seen in broken or cut pieces.
Hardness: Can scratch materials softer than 6 but is scratched by harder materials.
Luster: Look for a vitreous luster, particularly on surfaces that are not cleavage planes.

Locations: Significant deposits of amazonite can be found in Colorado, USA, particularly at Pike’s Peak, which is famous for its high-quality specimens. Other notable locations include Madagascar, Russia, Brazil, and parts of Africa.

Uses and Significance: Amazonite is used primarily as a gemstone and ornamental stone. It is popular in jewelry making for its color and relatively good durability. In addition to its aesthetic use, amazonite is sometimes considered in metaphysical circles to have calming and balancing properties.