Yellow dendritic crystal opal

BackCountryGal · Oct 28, 2006

I''ve been trying to find other locations/sources of the type of stone I have: super clear facet grade yellow to amber (few red) colored opal with dendritic trees and snowflake patterns. The ones we have came from a small one-horse mine on patented ground in central Idaho.
I can''t find any but I know there have to be others out there. (there is an undeveloped ridge of it near a lake we fish, so there IS more.) When I get my pendant out of uncle''s safe in Elko I''ll post a photo.

Richard Sherwood · Oct 28, 2006

Hi B.C. Gal. Would love to see some pictures. Your description sounds more like agate (quartz) than opal though. Opal is a sedimentary amorphous (non-crystalline) stone, while what your describing sounds like crystallization patterns.

Richard M. · Oct 28, 2006

Date: 10/28/2006 7:27:41 PM
Author:BackCountryGal
I''ve been trying to find other locations/sources of the type of stone I have: super clear facet grade yellow to amber (few red) colored opal with dendritic trees and snowflake patterns. The ones we have came from a small one-horse mine on patented ground in central Idaho.

This image is a 4.22 ct. yellow opal from Idaho -- near Garden Valley as I recall. It''s similar to yellow facet-grade opals produced in Mexico and Africa. As I remember the Idaho deposit produces a wide range of colors and patterns, including dendritic opal. I have dendritic opals from several locations including blue material from Peru.

Richard M.

Richard Sherwood · Oct 29, 2006

I stand corrected. God I love this forum. Thanks Richard.

Richard M. · Oct 29, 2006

Richard S.,

This is very high quality dendritic opal from another location in Idaho near the Western edge of the state. The term "crystal" opal is confusing and probably should be abandoned IMO. In the new grading scheme put together by the Gemmological Association of Australia it was left standing only because it''s commonly in use to describe certain types of transparent precious opal even though opal is amorphous, as you say, and basically has no crystal structure. (I say "basically" because there are opals from another location in Idaho that bring that statement somewhat into question -- grist for another thread sometime).

Facet-grade transparent common opal or potch (no play of color) can occur in many hues. I personally know of clear white, yellow, amber, orange, red, blue, brown and black. Dendrites often form in many non-crystalline or cryptocrystalline materials. In fact I''m not sure I''ve ever encountered them in any crystalline mineral [wracking brain].

Richard M.