Holley Blue Agate Identification Guide
Identify the prized lavender-blue Holley Blue agate from Oregon by its translucency, purple-blue color, and Cascade volcanic origin.
Read the full Holley Blue Agate encyclopedia entry →
What Holley Blue Agate Looks Like
Holley Blue is a rare, highly prized lavender-to-blue chalcedony (agate) found only near Holley, in the Cascade foothills of western Oregon. It is a microcrystalline quartz, and its appeal lies in a soft periwinkle-blue to purple color rarely seen in natural agate.
- Color: lavender, periwinkle blue, blue-purple to deep amethystine purple; the best pieces are saturated violet-blue.
- Luster: waxy to vitreous; glassy when polished.
- Transparency: translucent — light passes through, giving it a glowing quality.
- Habit: nodules, seam fillings, and waterworn pebbles; sometimes faintly banded or cloudy with wispy structure.
Field-ID Checklist
- Confirm the translucent lavender-blue/purple color — its signature.
- Hold it to light: genuine Holley Blue glows and transmits light rather than being opaque like jasper.
- Check hardness — it scratches glass and steel (about 7).
- Look for a waxy luster and conchoidal fracture typical of chalcedony.
- Confirm Oregon Cascade origin if possible — the locality is part of its identity and value.
Key Diagnostic Tests
- Mohs hardness: 7 (quartz) — scratches glass; not scratched by a knife.
- Streak: white.
- Cleavage/fracture: none; smooth conchoidal fracture.
- Density: ~2.6 g/cm3.
- Acid/magnetism: inert; non-magnetic.
- UV/translucency: strong translucency under a flashlight is a quick authenticity check versus dyed opaque imitations.
Common Look-Alikes
- Dyed blue agate / dyed chalcedony: mass-market dyed agate is often more uniform, intensely blue, and may show color concentrated along fractures; Holley Blue's color is more delicate, lavender-leaning, and natural-looking.
- Blue lace agate: has distinct white lacy banding and is paler powder-blue; Holley Blue is more purple and less banded.
- Ellensburg blue agate: another rare natural blue agate, but from Washington; color and locality differ.
- Chalcedony stained by chrysocolla (gem silica): more greenish-turquoise and tied to copper deposits, not the violet of Holley Blue.
- Amethyst: crystalline (transparent quartz crystals), whereas Holley Blue is massive microcrystalline chalcedony.
The practical fingerprint: translucent natural lavender-to-violet chalcedony with waxy luster, hardness 7, from the Holley, Oregon area.
Where It Is Found
It occurs almost exclusively around Holley and the Calapooia River / Sweet Home area of Linn County, Oregon, weathering from volcanic rock of the Western Cascades. The original claims are largely worked out, which is why authentic rough is scarce and valuable.
Frequently asked questions
How can you tell if Holley Blue agate is real?
Authentic Holley Blue is translucent natural lavender-to-violet chalcedony that glows when backlit, has a waxy luster, and is hardness 7 (scratches glass). Be wary of uniformly intense blue dyed agate; natural Holley Blue is softer-toned and purple-leaning, and genuine material comes from the Holley, Oregon area.
What does Holley Blue agate look like?
It looks like a glowing, translucent stone in soft periwinkle blue to violet-purple, sometimes faintly cloudy or banded, with a glassy polish.
Why is Holley Blue agate so expensive?
It comes from a single small area near Holley, Oregon, where deposits are largely exhausted. Its rare natural blue-purple color and limited supply make quality rough scarce and valuable.
Holley Blue agate vs blue lace agate — how do they differ?
Blue lace agate is pale powder-blue with prominent white lacy bands, while Holley Blue is more lavender to violet-purple and shows little to no banding. They also come from different localities.
Holley Blue Agate identified by the community
Recent Holley Blue Agate specimens identified with Rock Identifier.
