MODE XT. GNEISS. 



STRUCTURE V. MINGLED. 



Grey gneiss, with garnets, from Bohemia. 



The same, with actinote, from the same. 



The same, with pyrites, from Bohemia. 



The same, with different metals, from various 

 countries. 



Finite, with gold pyrites and native gold, from 

 Macugnaga. 



The same, with native gold, from Salzburg. 



The following examples of various kinds may 

 be added, from Saussure : 



A remarkable gneiss, of a bluish grey mica, in- 

 closing long grains of quartz and felspar, which 

 appear like sand, but are in fact crystals more or 

 less regular. 12Q1. 



A gneiss, composed of irregular layers of white 

 granular quartz, and leaves of a substance inter- 

 mediate between slate and steatite. 2044, 



A fine gneiss, composed of black mica, ap- 

 proaching in splendour to graphite, intermixed 

 with particles of felspar, and sprinkled with small 

 garnets. 1732. 



A gneiss, composed of grey felsite and grey 

 mica. 1877. 



A gneiss of foliaceous mica, with plates of 

 quartz, sometimes mixed with felspar, forms the 



