Ajkaite (Ajka Coal Fm./Csehbánya Fm., ~86.8-83.4 Ma)

"Ajkaite"
Ajka-Csingervölgy, Ajka District, Hungary
Ajka Coal Fm./Csehbánya Fm.
(~86.8-83.4 Ma)

Chemical Composition: C: 80%, H: 10%, O: 9%, S: 1-2%
Refractive Index: 1.541
Specific Gravity: 1.0

Weight of Specimen: 2.4g
Dimensions: 18x14x13mm

Lighting: Longwave UV (Convoy S2)

Ajkaite is a fossil resin with chemical composition markedly different from succinite (i.e., Baltic amber); it also contains low levels of sulfur. Ajkaite is found within layers of fossiliferous marl (numerous fossil shells can be seen in the matrix in the images): the marl is also accompanied by layers of coal, sand, sandstone, and siltstone. Ajkaite is found in both the Ajka Coal Fm. and the Csehbánya Fm., which two Formations are roughly the same age, and laterally transition into each other.

The coal mines roughly 4km southeast of Ajka first began production in 1872, and continued until the last mine was closed on September 3, 2004. Now, Ajkaite specimens can only be found in spoil-banks or refuse piles (Jókai coal refuse) near the city.

Various arthropods have been found trapped within Ajkaite, e.g., Araneae (spiders), Diptera (flies), Coleoptera (beetles), and Hymenoptera (ants, wasps). Since much of this amber is typically cloudy, X-ray tomography (CT scan) is often used to visually document the inclusions.