Ruby and Scapolite from the Rose Road Location, St. Lawrence County, New York
Contributed by: Michael Crawford
Date: Nov 9th, 2025
Locality: Rose Road, Pitcairn, St. Lawrence County, New York, USA (See on Mindat)
Size: 4 x 6.5 cm
Description:
A sawn specimen of scapolite and corundum var. ruby from the Rose Road location, Pitcairn, St. Lawrence County, New York. The red ruby in the specimen fluoresces red under longwave UV light and is surrounded by a non-fluorescent white mineral that is nepheline.
The numbers on the annotated image show the locations of the longwave emission measurements. The emission spectrum of the ruby (#1) has a very sharp, intense peak at 692 nm. There are much smaller peaks on both sides of the intense peak at 659 nm, 669 nm, 705 nm, and 713 nm. This emission signature of ruby is activated by chromium (Cr3+) replacing aluminum.
The scapolite fluoresces bright yellow under longwave light. The scapolite has vibronic emission peaks caused by a disulfide activator with an overall maximum at 577 nm and a small chromium activated peak at 692 nm (#2). Further analysis is needed to determine if the chromium peak in the spectrum is caused by a mixture of ruby and scapolite, or chromium replacing aluminum in the scapolite structure. There is an orange, fluorescent grain amongst the ruby (#3 in the annotated image). The emission spectrum of this grain shows a sharp peak at 692 nm and smaller peaks at 669 nm and 713 nm like the ruby spectrum. It also shows subtle peaks at 603 nm, 621 nm and 642 nm indicating disulfide activation of scapolite fluorescence. This may be a mixture of the two minerals.
There is a blue, fluorescent mineral that has a broad emission peak with a maximum around 460 nm. The mineral may be talc.
Summary of luminescence responses:
Corundum var. Ruby (Mindat) (RRUFF)
- Fluorescence under Longwave (365nm LED) UV light: Red
- Fluorescence under Longwave (365nm LED) UV light: Yellow