What is anorthite?
Anorthite is the calcium-rich end member of the plagioclase feldspar series. It is an important rock-forming mineral in mafic igneous rocks and also occurs in calcium-rich metamorphic assemblages and extraterrestrial material.
Mineralogy and structure
Anorthite has the formula CaAl2Si2O8 and crystallises in the triclinic system. Mohs hardness is about 6-6.5 and specific gravity is close to 2.75. Feldspar cleavage and polysynthetic twinning are important diagnostic features.
Colour and appearance
Colourless, white and grey material is common, while reddish or brownish tones may reflect inclusions and alteration. Crystals may be short prismatic, tabular, lamellar or granular, and twinning can create fine visible striations.
Formation and localities
Anorthite crystallises in calcium-rich basalt, gabbro and anorthosite, and it occurs in high-temperature metamorphic rocks. Important localities include Italy, Japan, the United States, Norway, Russia and lunar or meteorite samples.
Identification and collecting
Observe cleavage, twinning, host rock and composition. Intermediate plagioclase compositions are common, so a laboratory analysis may be required before assigning a specimen to the anorthite end member.
Anorthite and zodiac signs
In popular birthstone and zodiac guides, Anorthite is often associated with Taurus and Cancer. These zodiac crystal associations are part of modern spiritual culture and vary between traditions, countries and individual practitioners. They are not a mineralogical classification and should not be presented as a scientific property of the stone.
Esoteric meaning of Anorthite
Crystal collectors and readers of esoteric symbolism may choose Anorthite for its colour, texture, locality and personal meaning. In crystal healing and meditation traditions, it may be described with themes such as focus, grounding, protection, calm or confidence, depending on the source. These symbolic interpretations can be useful for storytelling and personal reflection, but there is no reliable scientific evidence that a mineral changes health, energy, luck or destiny.
Choosing Anorthite as a birthstone or symbolic crystal
When choosing a Anorthite birthstone, zodiac crystal or spiritual gift, compare the actual specimen: natural colour, crystal habit, transparency, inclusions, locality and condition. A mineral guide is more reliable when symbolic associations are kept separate from tested physical properties and from the description of an individual piece.
