Amber, Sumatra, Indonesia
Contributed by: Chris Clemens
minID: VCD-6HW
Date: Apr 18th, 2026
Locality: Sumatra, Indonesia (See on Mindat)
Size: 66 x 52 x 79 mm
Weight: 122 g
Description:
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 longwave. Brief yellow-green phosphorescence/afterglow is seen following exposure to longwave UV. Blue fluorescence is also seen under shortwave UV (254 nm) but is not as bright as the long wave response.
Originally posted by Chris Clemens on Nature's Rainbows in 2020.
Summary of luminescence responses:
Amber (Mindat) (RRUFF)
- Fluorescence under Longwave (365nm LED) UV light: Blue
- Fluorescence under Shortwave (254nm Lamp/Mercury) UV light: Blue
- Afterglow after exposure to Longwave (365nm LED) UV light: Green