Lemon Opal - Manhattan Mine

Contributed by: Daniel C. Montero
minID: M4Y-LFF
Date: May 5th, 2026
Locality: McLaughlin Mine (Manhattan Mine), Knoxville, Knoxville Mining District, Napa County, California, USA (See on Mindat)
Size: 40 x 30 x 70 mm

Description:
Lemon opal from the McLaughlin Mine, (Manhattan Mine) Knoxville, Knoxville Mining District, Napa County, California, USA

Unusual yellow fluorescence for opal. UV photo illuminated 365 nm longwave.

Originally posted by Daniel C Montero on Nature's Rainbows in 2021.

Fluorescence under longwave UV light.

Normal light.

Fluorescence under longwave UV light. Side 2.

Normal light. Side 2.

Summary of luminescence responses:

Opal (Mindat) (RRUFF)

• Fluorescence under Longwave (365nm LED) UV light: Yellow