occur, but not so commonly as fragments of plant tissues 
and organs. These fragmentary remains have created 
little enthusiasm on the part of botanists. Pollen and 
spores may be present, but they have received only lim- 
ited attention. This results probably from the fact that 
the microflora is difficult to see except in thin section, 
and that palynology has developed as a science since the 
great period of work onamber. Since evident inclusions 
are not common in some fossil resins and since these 
resins qualify as gems, mineralogists took on the task of 
routine physical and chemical characterization. Because 
the mineralogist’s interest did not lie specifically in the 
plant source of the resinous material, and as a result of 
the inherent difficulties of its determination, relatively 
little attempt has been made to synthesize botanical 
with chemical evidence for this purpose. 
CLASSIFICATION OF AMBERS 
Fossil resins from many parts of the world have been 
described in terms of some of the physical and chemical 
properties. Not only has the question of the plant source 
often been neglected, but the geological age of the de- 
posits frequently is not well documented. One of the 
most widely used classifications of fossil resins divides 
them into two series, with the succinites containing suc- 
cinic acid and the retinites lacking it (Dana, 1895; 
Hintze, 1933). More recently, Steuzel (1931) and Hey 
(1950) not only distinguished the succinite from the reti- 
nite series on the presence or absence of succinic acid, 
but set off a tasmanite series consisting of sulphur-bearing 
resins. Plonait (1985) and Hilterman (1949) indicated 
that these properties vary within the same species and 
should not be used as a basis of classification. Paclt 
(1958a) stated that the main criteria should be botanical 
derivation and the geologic age of the deposits. Accord- 
[ 227 ] 
