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“Kuji Amber” Hirono, Iwate Prefecture, Japan Tamagawa Fm. (Kuji Group) ~91.05-85.2 Ma Total Weight: 1.3g Longest Specimen: 10mm Lighting: Longwave UV Entry five of ten, detailing various rare ambers from European, Asian, and North American localities. Studies on this amber, and Japanese ambers in general, are especially fascinating from a pharmaceutical point of view. In early 2012, a particular diterpenoid was extracted from Kuji amber that has been shown to possess powerful anti-allergenic properties; this compound was named “kujigamberol”, and is extracted from powdered amber using methylene hydroxide (MeOH). In the case of powdered Iwaki amber, 18.5g of amber was added to MeOH for 3 days, after which the MeOH was evaporated leaving 0.8g of solid extract; further extractions and purification were applied, leaving 1.0mg of a colorless oil. Kujigamberol can be obtained from Kuji, Iwaki, Choshi, Mizunami, and Ube ambers, but its concentration decreases proportionally to the ambers’ age (i.e., the older the amber, the lower the yield). Kuji amber is found in exposures along the inner southern half of Kuji Bay, as well as further south at Noda Bay along the coastline, just north of the mouth of the Akka River: the exposures consist of sandstones, conglomerates, and amber-bearing carbonaceous mudstone (which also contains small plant fossils); the Tamagawa Fm. is roughly 200m thick, and amber is found within the middle and upper portions. Shell fragments of freshwater turtles can also be found in a bone bed within the uppermost portion of the Formation; immediately above the bone bed is a layer of volcanic ash containing zircon grains: these have been dated to be 91 million years old. The amber of the Kuji and Noda Bays is often found washed onto the shoreline as waterworn grains; there is a more well-known deposit inland, however, where amber is mined directly from the earth. Sources: “Comparison of the Biological Activity and Constituents in Japanese Ambers”; Advances in Biological Chemistry, Issue 10; Shimizu, et. al. 2020 “A New Assemblage of Plant Mesofossils (Late Turonian–Middle Santonian; Upper Cretaceous) from the Tamagawa Formation, Kuji Group, in Northeastern Japan”; Paleontological Research, Issue 25 (2); Masamichi Takahashi, et. al. 2021 “A New Species of Aquatic Turtle (Testudines: Cryptodira: Adocidae) from the Late Cretaceous of Kuji, Iwate Prefecture, Northeast Japan, with Special References to the Geological Age of the Tamagawa Formation (Kuji Group)”; Ren Hiyama, et. al. 2021

“Kuji Amber” Hirono, Iwate Prefecture, Japan Tamagawa Fm. (Kuji Group) ~91.05-85.2 Ma Total Weight: 1.3g Longest Specimen: 10mm Lighting: 140lm LED Entry five of ten, detailing various rare ambers from European, Asian, and North American localities. Studies on this amber, and Japanese ambers in general, are especially fascinating from a pharmaceutical point of view. In early 2012, a particular diterpenoid was extracted from Kuji amber that has been shown to possess powerful anti-allergenic properties; this compound was named “kujigamberol”, and is extracted from powdered amber using methylene hydroxide (MeOH). In the case of powdered Iwaki amber, 18.5g of amber was added to MeOH for 3 days, after which the MeOH was evaporated leaving 0.8g of solid extract; further extractions and purification were applied, leaving 1.0mg of a colorless oil. Kujigamberol can be obtained from Kuji, Iwaki, Choshi, Mizunami, and Ube ambers, but its concentration decreases proportionally to the ambers’ age (i.e., the older the amber, the lower the yield). Kuji amber is found in exposures along the inner southern half of Kuji Bay, as well as further south at Noda Bay along the coastline, just north of the mouth of the Akka River: the exposures consist of sandstones, conglomerates, and amber-bearing carbonaceous mudstone (which also contains small plant fossils); the Tamagawa Fm. is roughly 200m thick, and amber is found within the middle and upper portions. Shell fragments of freshwater turtles can also be found in a bone bed within the uppermost portion of the Formation; immediately above the bone bed is a layer of volcanic ash containing zircon grains: these have been dated to be 91 million years old. The amber of the Kuji and Noda Bays is often found washed onto the shoreline as waterworn grains; there is a more well-known deposit inland, however, where amber is mined directly from the earth. Sources: “Comparison of the Biological Activity and Constituents in Japanese Ambers”; Advances in Biological Chemistry, Issue 10; Shimizu, et. al. 2020 “A New Assemblage of Plant Mesofossils (Late Turonian–Middle Santonian; Upper Cretaceous) from the Tamagawa Formation, Kuji Group, in Northeastern Japan”; Paleontological Research, Issue 25 (2); Masamichi Takahashi, et. al. 2021 “A New Species of Aquatic Turtle (Testudines: Cryptodira: Adocidae) from the Late Cretaceous of Kuji, Iwate Prefecture, Northeast Japan, with Special References to the Geological Age of the Tamagawa Formation (Kuji Group)”; Ren Hiyama, et. al. 2021