Lemon Opal, Manhattan Mine, Knoxville, California

Lemon opal, also known as semi-opal, from the Manhattan mine in Knoxville, Napa County, California. Under long wave UV, the lemon opal shows a bright yellow fluorescent response. The fluorescence is similar under short wave UV, but not as bright. The size of this specimen is 42 x 40 x 30 mm.

The Manhattan mine, also known as the McLaughlin mine, is located on a hot spring type deposit that produced lead, gold, silver and mercury, beginning in the 1860s. This site is no longer available for collecting.

Lemon opal from the Manhattan mine, showing fluorescence under long wave UV (254nm).

Same specimen seen under visible light (left), short wave UV (middle) and long wave UV (right). Click on the individual images for a larger view.

39 views0 comments

Email comments or suggestions:


Nature’s Rainbows is a non-commercial web site maintained entirely by volunteer hobbyists and contributors.  Our mission is to provide information about UV and luminescence, premium fluorescent mineral photos, and a fluorescent mineral database for the enjoyment of FL mineral collectors around the world.  Information on this web site is covered under a Creative Commons License.

Feel free to contact us with comments and suggestions.

Like us on Facebook!

  • reddit
  • Facebook Social Icon

Subscribe to our RSS (Real Simple Syndication) feed to get new posts delivered directly to your desktop!