20 
jtooM viii. formation from Montmartre. Rock salt, consti- 
NaT. Hi.st. toting a formation nearly related to that of 
gypsum. 
(Dm. 8.) Containing porphyry, sienite and 
the trapp-foraiation.—Hornstone porphyry, from 
Scotland, Norway, Thuringia, Egypt, * &c„ 
(Egyptian antique porphyry with reddish grains 
of feldspar); porphyry with hornblende, with 
quartz veins ; variety with its base less hard, being 
the jasper porphyry of some mineralogists ; feld¬ 
spar porphyry from Frauenstein. Clay por¬ 
phyry; the -same, with the feldspar in severaj 
•stages of decomposition ; with mica (the Sax- 
urn metalliferum of Baron Born, being the 
principal repository of gold and silver ores 
in Lower Hungary and Transylvania) ; pitch- 
atone porphyry; porphyry balls; porphyry 
breccia or Trammer-porpbyr.—Porphyry slate. 
Sienite: (fragment of an Egyptian idol 
composed of much hornblende, reddish feldspar 
unequally distributed, and some mica: being the 
true Signites of Pliny); similarly grained, without 
•mica; with quartz (bianco e nero d'Egitto) ; 
porpbyritic sienite consisting chiefly of horn¬ 
blende appearing to pass over into hornblende 
slate.—Common hornblende rock,—Hornblende 
slate.—Greenstone.—Greenstone porphyry : por- 
Jido verde antico , or serpent bio vende antico, 
as 
