Sunstone in Depth
Feldspar full of metal flakes
Sunstone is another feldspar, usually oligoclase or labradorite, and its glitter comes from microscopic platelets that formed inside the crystal as it cooled. In most material those are hematite or goethite, giving a coppery orange spangle. In Oregon sunstone the inclusions are native copper, actual metallic copper suspended in the feldspar, which is geologically unusual and makes that material distinctive.
Oregon sunstone comes from basalt flows in Lake and Harney counties and is the state gem. Depending on copper concentration it ranges from clear to peach to red and green, and some stones show more than one color in different directions. Indian and Tanzanian sunstone is the common opaque orange sparkly material sold as tumbles. Hardness sits at 6 to 6.5.
Schiller and how to see it
The flash in sunstone is called schiller or aventurescence, and like every optical effect from included platelets it depends on angle. The platelets lie on specific planes inside the crystal, so a cut that ignores those planes gives you a dull stone. When it is cut right, direct light makes the whole piece appear lit from inside.
This is worth knowing when buying online, where photos are almost always taken at the one angle that shows the maximum flash. Ask what it looks like in ordinary indoor light. A good piece should still show something without a spotlight on it.
Care
Sunstone is a feldspar with two directions of good cleavage, so it chips at edges and can split under a sharp knock. Rings need protective settings. Store it away from quartz and harder stones.
Brief water contact is fine, but skip long soaks, ultrasonic cleaners, and steam, all of which exploit cleavage and can loosen included platelets near the surface. Salt is abrasive and will scuff the polish. Unlike its opposite number moonstone, sunstone is generally considered safe in sunlight, which makes it one of the few stones that can actually live on a sunny sill without complaint.
Use and companions
Sunstone is worked with for warmth, visibility, and enjoying things, which sets it apart from the other confidence stones. Where citrine is about drive and pyrite is about follow-through, sunstone is associated with being willing to be seen and with generosity that does not run you dry. It is a common recommendation for people who over-give quietly.
Leo is the primary sign link, with Libra also cited, and it works at the sacral and solar plexus. The classic pairing is with moonstone, the two set together as a solar and lunar pair for balance, and that combination is one of the oldest deliberate crystal pairings in modern practice. It also goes with carnelian for physical energy and with citrine when the goal is momentum.