21 
formation from Montmartre. Rocksalt, consti¬ 
tuting a formation nearly related to that of 
gypsum. 
( Div . 8.) Containing porphyry, sienite and 
the trappformation.—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 several 
stages of decomposition ; with mica ; (the Sax- 
um metalliferum of Baron Bom, being the 
principal repository of gold and silver ores 
in Lower Hungary and Transylvania) ; pitch- 
stone porphyry ; porphyry balls; porphyry 
breccia or Trummer-porphyr.—Porphyry slate. 
Syenite : (fragment of an Egyptian idol, 
composed of much hornblende, reddish feldspar 
unequally distributed, and some mi ca: the true 
Signites of Pliny) ; similarly grained, without 
mica ; with quartz (bianco e nero d’Egitto) ; 
porphyritic syenite consisting chiefly of horn¬ 
blende appearing to pass over into hornblende 
slate.—Common hornblende rock.—Hornblende 
slate.—Greenstone—Greenstone porphyry; por- 
fido verde antico, or serpentina verde antico, 
as 
ROOM VIII. 
Nat. Hist, 
