Lemon Opal, Manhattan Mine, Knoxville, California
Contributed by: Chris Clemens
minID: J5N-0FY
Date: Apr 22nd, 2026
Locality: McLaughlin Mine (Manhattan Mine), Knoxville, Knoxville Mining District, Napa County, California, USA (See on Mindat)
Size: 40 x 30 x 42 mm
Weight: 37 g
Description:
Lemon opal, also known as semi-opal, from the Manhattan Mine in Knoxville, Napa County, California. Under longwave UV, the lemon opal shows a bright yellow, fluorescent response. The fluorescence is similar under shortwave UV, but not as bright.
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.
Originally posted by Chris Clemens on Nature's Rainbows in 2018.
Summary of luminescence responses:
Opal (Mindat) (RRUFF)
- Fluorescence under Longwave (365nm LED) UV light: Yellow
- Fluorescence under Shortwave (254nm Lamp/Mercury) UV light: Yellow