What does andesine mean?
Andesine is a mineral belonging to the plagioclase feldspar group, one of the most abundant families of minerals in the Earth's crust. Chemically it sits midway between the sodium-rich end member albite and the calcium-rich end member anorthite, and it occurs commonly in intermediate igneous rocks such as andesite and diorite, typically appearing as grey, white, or reddish blocky crystals. The name derives from its presence in rocks of the Andes mountains. Although it is chiefly of interest to geologists, andesine has gained wider attention through the gem trade, where translucent specimens in shades of red, orange, and green have been marketed as collectible gemstones; buyers should note that some commercial 'red andesine' has been artificially treated to enhance its colour. For students of earth science, andesine serves as a useful marker mineral for classifying volcanic and plutonic rocks.
nounA mineral of the plagioclase feldspar group, a sodium-calcium aluminium silicate occurring as an intermediate member between albite and labradorite, typically red, pink, or grey in colour.
- The plagioclase feldspar mineral of intermediate sodium–calcium composition, found in igneous rocks.
- A variety of this mineral cut as a gemstone, often displaying red, orange, or green hues.
"The gem dealer identified the vivid red stone as andesine, a feldspar prized by collectors."
"Thin sections of the volcanic rock showed lath-shaped crystals of andesine under the microscope."
"Her ring held a striking orange-red andesine that caught the light beautifully."
Rarely pluralised; when referring to multiple crystals or specimens, the plural form is used mainly in technical writing.
"The collection contained andesines from several different localities."
This gemstone takes its name from the Andes mountains — but most of the 'red andesine' sold in jewellery stores today was actually treated to get that colour.
Reviewed by Deb Chak, Editor. AI-assisted content curated by RJS Tech Solutions LLP.
Etymology of andesine
Andesine was named after the Andes mountains of South America, where it was first identified in andesite lavas; the name follows the same geographic pattern as andesite itself. It belongs to the plagioclase feldspar family, whose members are distinguished chemically by their varying proportions of sodium and calcium. Related names such as labradorite (from Labrador) and albite reflect the same tradition of naming feldspars after places where they were first described.
How andesine is actually used
Andesine is used almost exclusively in geology, mineralogy, and gemmology; it is unfamiliar to most general readers. In the gem trade, the word often refers specifically to reddish gem-quality material, some of which has been colour-treated.
Easily confused with andesine
Andesine is a feldspar mineral, whereas andesite is a fine-grained volcanic rock named after the Andes.