Ia
Includes Succinite (= 'normal' Baltic amber) and Glessite. Have a communic acid base. They also include much succinic acid.
Baltic amber yields on dry distillation succinic acid, the proportion varying from about 3% to 8%, and being greatest in the pale opaque or bony varieties. The aromatic and irritating fumes emitted by burning amber are mainly due to this acid. Baltic amber is distinguished by its yield of succinic acid, hence the name succinite. Succinite has a hardness between 2 and 3, which is rather greater than that of many other fossil resins. Its specific gravity varies from 1.05 to 1.10. It can be distinguished from other ambers via IR spectroscopy due to a specific carbonyl absorption peak. IR spectroscopy can detect the relative age of an amber sample. Succinic acid may not be an original component of amber, but rather a degradation product of abietic acid.
Read more about this topic: Amber, Classification, Class I