Yttrofluorite - Joseph Mine, Rio Arriba County, New Mexico

Contributed by: Chris Clemens
minID: D60-AJF
Date: May 23rd, 2026
Locality: Joseph mine, Ojo Caliente Mining District, Rio Arriba County, New Mexico, USA (See on Mindat)
Size: 47 x 34 x 64 mm
Weight: 115 g

Description:
Yttrofluorite is a variety of fluorite in which the rare earth element yttrium substitutes for some of the calcium in the fluorite (CaF₂) structure. This specimen consists of a solid piece of white to pale green yttrofluorite with no matrix. This piece was collected in 2000 at the Joseph Mine, Rio Arriba County, New Mexico.

As shown in the following photographs, this yttrofluorite specimen shows a multi-colored, multi-wavelength fluorescent response under UV. Bright pale-yellow fluorescence under shortwave UV (254 nm). Pale blue fluorescence under midwave UV (302 nm). Blue fluorescence under longwave UV (365 nm).

Originally posted by Chris Clemens on Nature's Rainbows in 2022.

Fluorescence under longwave UV light.

Fluorescence under midwave UV light.

Fluorescence under shortwave UV light.

Normal light.

Summary of luminescence responses:

Yttrofluorite (Mindat) (RRUFF)

• Fluorescence under Longwave (365nm Lamp/Mercury) UV light: Blue
• Fluorescence under Midwave (305nm Lamp/Mercury) UV light: White
• Fluorescence under Shortwave (254nm Lamp/Mercury) UV light: Yellow