Uranium glass

Uranium glass is glass which has had uranium (U), usually in oxide diuranate form, added to a glass mix before melting for coloration. The proportion usually varies from trace levels to about 2% by weight uranium, although some 20th-century pieces were made with up to 25% uranium [1].

The sample being studied here (figure 1) was kindly donated by Pierre Leglise - Comptoir optique - Charleroi - Belgium.

Such a glass is known to be highly responsive to UV exposure with a green luminescence, bright green under long-wave UV (figure 2) and chalky green under short-wave UV.  

uran glass medFigure 1. The uranium glass showing its pale yellow color in daylight

Shape  flat rounded
Size  24.2 x 18.3 x 6.3 mm
Color  pale yellow
Lustre  vitreous
Transparency  translucent
Weight  21.75 ct
SG  2.56
RI  -
DR  -
Pleochroism  not applicable
Polariscope / Conoscope  anomalous extinction (dark cross appear to writhe like snakes)
SWUV  chalky green
LWUV  bright green (see figure 2)
Magnetic suceptibility  inert
Radioactivity  radioactive small  1.1 to 1.4 µSv/h (~240 to 300 cpm)

Table 1. Observational and measured properties

uv365 uran glassFigure 2. Exposed to a 365 nm source (long-wave UV), the glass 'glows' bright green.

Photoluminescence spectroscopy:

This uranium glass easily glows green even with low power led, no need of laser to get such amazing luminescence. The corresponding emission spectrum is available in figure 3 and shows the characteristic UO22+ emission.

pl405 uranium glass 2175 pale yellow
Figure 3. The 405 nm excitation photoluminescence spectrum of the uranium glass shows the characteristic spectrum of UO22+.


A piece of man-made glass glowing bright green under LWUV for which the luminescence cause is easily explained using photoluminescence spectroscopy. The material owes its bright green luminescence to UO22+. Note that the material is sligtly radioactiv with 1.1 to 1.4 µSv/h.