SYSTEMATIC PETROGRAPHY S577 
Morphology, a classification of forms of occurrence. 
Synopsis, or the systematic descriptive science. 
Petrogeny, a discussion of the genesis of rocks. 
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Allo-osology, the science of the alteration of rocks. 
Under this elaborate framework rocks were grouped in many 
ways. They were considered as minerogenous, zoégenous, or 
phytogenous, according to origin of materials; as crystalline, 
clastic, dialytic, or amorphous, depending on character of the 
constituent grains; as simple or composite; in another view as 
phanomeric or cryptomeric, and so on. 
But when it came to the systematic arrangement of his 
“Synopsis” Naumann was at sea. He himself called it an 
attempt at a grouping of rocks—‘ Ein Versuch einer Gruppirung 
der Gesteine’’—and plunged without discussion of principles 
into the description of rocks under a scheme of classes, orders, 
families, and lesser divisions. 
In the first edition of the Lehrbuch, Naumann divided all 
rocks into three classes, namely: (1) Crystalline rocks; (2) 
Clastic rocks; (3) Rocks which are neither crystalline ‘nor 
clastic. 
It was explained that the groups of amorphous, zodgenous, 
and phytogenous rocks are scarcely co-ordinate in importance 
with the crystalline and clastic divisions, so they were united in 
the third composite class. In the descriptions of the Synopsis, 
however, the amorphous (hyaline and porodine) rocks were con- 
sidered in connection with the rocks of the other two classes to 
which they are related in composition. 
In the second edition but two classes were recognized, 
embracing all rocks: (1) Protogenous (original); (2) Deuter- 
ogenous (derived). Naumann gave no discussion of the basis 
upon which he made the change. 
In both editions Naumann leaves the manner of subdividing 
classes to the reader to make out for himself. In the class of 
original rocks are six orders, viz.: (1) Ice, (2) Haloid rocks, (3) 
Quartz rocks, (4) Silicates, (5) Ores, (6) Coal. Families are pro- 
duced within these orders by mineral composition. Structure, 
