Martins,
It was sad to hear about this loss.
My only wonder is about your estimated weight of 15 tons. A cylinder with a diameter of 1 m and a lengt of 1,9 m. will have a volume of: 3,14 x 0,5 x 0,5 x 1,9 = approximately 1,5 cubic meters, With a density of 3,5-4 ( mainly quartz ? ) the estimated weight of the log would be no more than 5-6 tons and this can explain why it may have been possible to lift it on a truck and drive away.
Hopefully the specimen will be recovered and guarded in a museum.
Knut