Amber, Sumatra, Indonesia
This is an excellent example of brightly fluorescent amber, from a relatively new find in the coal deposits of the Bukit Barisan (Barisan Mountain Range) on the western side of Sumatra. This material is known as "black amber" due to its very dark color. This material is found in the coal seams of the Sinamar Formation, and was formed approximately 30 million years ago by the fossilization of an ancient forest of Hymenaea Protera trees (this species is now extinct). Under UV, this amber fluoresces a beautiful sky blue color, brightest under long wave. The size of this specimen is 79 x 66 x 52 mm, and it weighs 122 grams.
Bright, sky blue colored fluorescence in seen in the above photograph, taken under long wave UV (365 nm).
As shown above, brief yellow-green phosphorescence/afterglow is seen following exposure to long wave UV.
Above, blue fluorescence is also seen under short wave UV (254 nm), but is not as bright as the long wave response.
Above, same specimen, shown under visible light.
Photo montage showing the UV response compared to the visible light image.