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Willemite and Sphalerite, Miller Canyon, Arizona

This lovely 2-color fluorescent specimen contains willemite and sphalerite, and is from the Nelly James Mine (also known as Miller Canyon), in southern Arizona. As shown in the photographs below, the willemite fluoresces bright green under short wave UV, while the sphalerite shows an orange response under long wave UV. This rock is best viewed under short and long wave UV at the same time to simultaneously see the green fluorescence of the willemite in combination with the orange response of the sphalerite. The size of this colorful specimen is 75 x 68 x 47 mm, and it weighs 300 grams.

Miller Canyon is located in the rugged terrain of the Huachuca Mountains, in Cochise County, Arizona. Near the top of Miller Canyon lies the Nelly James mine. The hike to the Nelly James is 3 miles long, and requires a vertical elevation gain of 1500 feet over challenging tread. Being located close to the Mexican border, Miller Canyon provides a route to illegal immigration and drug smuggling into the US, so presents a real possibility of risky encounters on the trail. Despite the risks, the Nelly James mine has been a productive source of beautiful, multi-colored fluorescent minerals such as this fine example.

Shown in the above photograph, taken under full wave UV (SW+MW+LW), the willemite fluoresces bright green and the sphalerite shows an orange response.

As shown above, only the green fluorescent response of the willemite is seen under short wave UV (254 nm).

Under long wave UV (365 nm), only the orange fluorescence of the sphalerite is seen.

As shown above, the sphalerite shows a strong phosphorescent response following exposure to long wave UV (365 nm).

As is the case with many fluorescent mineral specimens, this rock looks pretty drab under visible light.

The Nelly James was a small open pit lead, copper, zinc, gold and silver mine located in Miller Canyon, in the Huachuca Mountains, Cochise County, Arizona. Its history lasted from the 1880’s until 1915 or so. The small amount of ore produced by the Nelly James was inconsistent with the size of the operation, leading to speculation that the property was more of a prospect, and may have been part of a stock scam. The good news to fluorescent mineral collectors is that to this day, the Nelly James mine has been a productive source of beautiful fluorescent minerals. The specimen featured here was collected in March of 2020 by Ken and Gail Hennig.

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