254 HAROLD L. ALLING 
writer has merely extended the term “potash” as given to the 
feldspar from Tyveholmen, Norway, to other plagioclasic feldspars 
with a potash-component content greater than 10 per cent. The 
prefixes hypo-, eutecto-, and hyper- have been pointed out before as 
adaptations of metallographic nomenclature. The term ‘‘oranite”’ 
is employed for feldspars of the potash-lime ranges analogous to 
perthite. The derivation of the term is indicated by the first 
two letters of orthoclase and anorthite with the mineralogical 
ending -ite. Thus with these prefixes and the term ‘‘oranite”’ 
many areas can be supplied with suitable names. In the triangles 
between hypoperthite and hypo-oranite the proposed terms ‘‘para- 
perthite” and “‘para-oranite”’ are not very satisfactory. The Greek 
Tapa- possesses a wide range of meanings, one of which implies ‘‘a 
position alongside of” and ‘‘beside of,’ which is the meaning 
desired here. Criticism of the term, however, may be made on 
the ground that the geologist and the mineralogist use paragneiss, 
paraschist, paragenesis, paramorphism, paramorph, etc., without 
attaching this significance to the prefix. It is a term which can 
be temporarily used until a better one is found. 
EXAMINATION OF CHEMICAL ANALYSES OF FELDSPARS 
It is very desirable to know what is the actual composition of 
natural specimens of feldspars, and how these have been classified. 
Consequently many chemical analyses have been examined. 
About 1,300 analyses of feldspars from all parts of the world were 
collected from the literature. Of this number 954 were considered 
to be suitable for recasting and plotting. In dealing with such a 
large number of analyses it was obviously impossible to recast 
each by first obtaining the molecular ratio of each oxide and 
combining them in the usual manner. Therefore short cuts to 
approximately the same results were used. It was first assumed 
that each specimen was composed of only three components, the 
potash, soda, and lime feldspars, excepting in case where BaO was 
determined, indicating the presence of celsian. 
The percentage of each component was determined directly 
from the percentage of the characteristic base. Thus all of the K,O 
was assumed to be in KAISi,O3; all the Na.O in NaAISi,Os, and 
