What Is Sunstone? The Sparkle Is a Different Effect Than Moonstone's

Sunstone belongs to the same broad feldspar family as moonstone and labradorite, but produces a third, distinct optical effect called aventurescence (also called the schiller effect).

How Aventurescence Works

Unlike moonstone's light-scattering glow or labradorite's interference-based flash, sunstone's sparkle comes from thin, flat platelet inclusions — typically copper or hematite/goethite — scattered through the stone. These platelets act like countless tiny mirrors: light striking them at the right angle reflects directly back, producing a glittery sparkle rather than a diffuse glow or a sharp color flash. The effect is strongest when the stone is cut so its face aligns with the general orientation of those internal platelets.

Oregon's Unique Material

Most sunstone worldwide gets its platelets from hematite or goethite. Oregon sunstone (the official state gemstone) is unusual in containing genuine copper platelet inclusions instead — a distinct and less common origin that also allows some Oregon material to show a reddish-green color shift depending on copper concentration, on top of the standard sparkle effect, making it a genuinely different variety from most commercial sunstone.

Where Else It's Found

India and Norway are other significant sources, generally producing the more common hematite/goethite-platelet type of material.

Quick Facts

Mineral family: feldspar — Hardness: 6–6.5 on the Mohs scale — Optical effect: aventurescence, from reflective platelet inclusions — Oregon material uniquely contains copper platelets — Major sources: USA (Oregon), India, Norway.