Other amber mining sites are the Baltic coast and the Dominican Republic, but only 90 million years ago is Kuji. At that time, it was just the age of dinosaurs, and the sap became fossils over a long period of time. Furthermore, it is an event before the Japanese archipelago was torn from Eurasia and evidence that Kuji was part of Eurasia.
Amber was discovered as a jewelry in the remains of 20,000 years ago, and is still an attractive gemstone. Compared to mineral gemstones, they are much lighter and warmer than I expected due to their resin origin.
Amber with insects is even more expensive. The fiction setting of the movie “Jurassic Park” is to extract dinosaur blood and DNA from mosquitoes in amber and restore real dinosaurs. Maybe you could get a ticket to travel to the dinosaur era ! jejeje!