Scapolite, Ruby and Calcite from Xinjiang Province, China
Contributed by: Michael Crawford
Date: Jun 24th, 2025
Locality: Xinjiang, China (See on Mindat)
Size: 4 x 6.5 cm
Description:
This specimen contains two of the brightest longwave UV fluorescent minerals, ruby and scapolite. The ruby fluoresces red, and the scapolite fluoresces yellow. Their identities were confirmed by emission spectra. Ruby has a sharp peak at 692 nm and much smaller peaks at 669 nm and 713 nm caused by a chromium activator. The scapolite has vibronic peaks caused by a disulfide activator with an overall maximum at 578 nm and a small chromium activated peak at 692 nm.
The specimen comes from Xinjiang Province, China. This fluorescent combination is uncommon. It can also be found at the Rose Road location, St. Lawrence County, New York. This Chinese specimen has a third fluorescent mineral that glows blue in MW illumination only. A drop of acid on the mineral causes it to fizz indicating that calcite is the blue, fluorescent mineral.
Summary of luminescence responses:
Corundum var. Ruby
- Fluorescence under Longwave (365nm LED) UV light: Red
- Fluorescence under Midwave (305nm LED) UV light: Red
- Fluorescence under Shortwave (255nm LED) UV light: Yellow
- Fluorescence under Longwave (365nm LED) UV light: Yellow
- Fluorescence under Midwave (305nm LED) UV light: Yellow
- Fluorescence under Midwave (305nm LED) UV light: Blue