Hell Creek Formation amber

A typical example of amber from the Hell Creek Fm. of Montana. Reddish-orange varieties (photo left) to deep red varieties (photo right) are the most common colors found in the Formation. Yellow color varieties are present, but they all have a powdery appearance, and may represent amber that has been oxidized. Oxidation causes amber to become opaque, yellow, and crumbly (photo left). So far, I have not seen any uncolored transluscent varieties. Compared to Tertiary-age amber, the Cretaceous-age Hell Creek Fm. amber is less abundant and is smaller. The material that I have seen is EXTREMELY friable (friable = easily crumbles). This amber is so fragile that it will sometimes crumble into dust if you try to pick it up with tweezers or even with your fingers! The specimen was not coated with any preservatives, but I have put preservatives on other Hell Creek amber, particularly if the pieces are going to be handled. Preservatives darken the amber significantly, and I have found that they impart an undesirable appearance. Both shale and lignitic zones are uncommon in the Hell Creek Formation; most fine-grained Hell Creek rock is massive mudstone.
Not all Hell Creek Formation amber is as diminutive as are the specimens I have illustrated here. Check out an article in the November, 1993 issue of Lapidary Journal (page 41).