Orthoclase is potassium feldspar, a very common mineral usually seen as pale pink, white or cream crystals. In jewelry it mostly turns up as moonstone, which is orthoclase layered with albite.
Silicate (tectosilicate, alkali feldspar)
Orthoclase
Ortoclasa
- Palette
- White Pink Yellow Clear
- Mined in
- United States, Russia, Switzerland, Germany
- Hardness
- Mohs 6.0 ?
- See-through
- translucent
- Known since
- 1823
- Named for
- Greek for 'straight fracture', for its right-angle cleavages
- Also sold as
- potassium feldspar, K-feldspar, K-spar, adularia (a form of it)
- Intention
- New Beginnings Love
- Looking for
- Luck Hope Love
- Water
- Keep it dry; wipe with a soft cloth
- Dye or finish
- No seller or lab page we read says orthoclase is dyed, heated, or filled; it is normally sold natural, and moonstone glow is natural.
Not in our pieces now
90°
Orthoclase's name means 'straight fracture,' because its two cleavage planes meet at right angles.
FLORIDA
Moonstone is Florida's state gem, chosen in 1970 to mark the Moon landings, though it does not occur naturally in the state.
MARS
NASA's Curiosity rover found abundant orthoclase in Martian sandstones.
What it is
A common feldspar in pale pink, white, cream or greenish crystals with two flat cleavage faces at right angles, seen mostly as mineral specimens and cut stones. In beads it is usually sold as moonstone, which is orthoclase intergrown with albite.
Where it comes from
Orthoclase was first described from the Adula Alps in Switzerland and is also known from the Organ Mountains in New Mexico and the Ural Mountains in Russia. Moonstone comes mostly from Sri Lanka, with India and Madagascar, and Myanmar historically.
In history
Orthoclase is the feldspar behind most moonstones, and the Romans admired moonstone, associating it with their lunar deities; René Lalique and other Art Nouveau goldsmiths later set it in a large quantity of jewelry. The silky-glowing form called adularia was first described by Ermenegildo Pini in 1781, and the largest single crystal known, about 100 tonnes, was found in Russia's Ural Mountains.
What's said about it
It has little lore under its own name. In crystal lore, moonstone is the stone people keep for intuition and wishes, and orthoclase borrows that reputation.
In older gem lore, moonstone was thought to bring good fortune, and in India it was held sacred. The name orthoclase is Greek for straight fracture.
Bracelet makers use moonstone; orthoclase itself is mostly a collector's piece.
How people wear or keep it: In a pocket, by the bed, on a shelf, or on the wrist (as moonstone).
In crystal practice
Day to day, the same tradition suggests keeping it close: in a pocket, by the bed, on a shelf. People reach for it when they want luck, hope, love, and many set an intention when they put it on. Most practitioners cleanse a new stone first (running water only if the stone can take it, otherwise smoke or moonlight) and set it aside now and then to rest.
These are beliefs people have held and still hold about the stone, reported as such. Nothing here is a promise or a medical claim. We sell stones as jewelry, not for these effects.
Associations
The chakra and star sign this stone is usually matched with. These are popular traditions, not facts about the stone.
ZodiacCancer
ElementFire
Also calledpotassium feldspar, K-feldspar, K-spar
Care
- Hardness 6, but it has two perfect cleavages and can split on a knock, so keep it out of drops.
- Store it apart from harder stones such as quartz.
- Wipe with a soft cloth; avoid ultrasonic cleaners and sudden heat.
- Keep it away from water and salt as a precaution; the stone is fine, but beads can have glued or coated finishes.
How to tell what you have
- Orthoclase is hardness 6 with two split directions at right angles, glassy, in colorless, yellow, pink, or white.
- Gem moonstone is orthoclase with a milky blue glow; 'rainbow moonstone' is a different mineral (labradorite).
- A glow that floats on the surface of an otherwise clear glassy stone can be glass.
Questions people ask at our table
What is orthoclase?
It is potassium feldspar, one of the most common minerals in the Earth's crust. It is the reference mineral for hardness 6 on the Mohs scale.
Is moonstone orthoclase?
Mostly, yes. Most moonstone is orthoclase intergrown with albite, and that layering gives the soft glow.
Is it natural or dyed?
Crystals are natural. Pink or other bright beads sold under feldspar names may be dyed, so ask the seller.
Where is it found?
Almost everywhere in granite and similar rock. Well-known crystals come from the Ural Mountains in Russia, the Swiss Alps, Germany and New Mexico.
Do you carry orthoclase?
No, we do not carry it. Moonstone, amazonite and labradorite are feldspars in our pieces; moonstone is the nearest.
Not in our pieces right now
Stones we do carry that are close to it are listed under related stones.
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