53 
tilting a formation nearly related to that of roomV-iii. 
gypsum. Na"st. 
(Shelves 5 and 6.) Porphyry. — Hornstone cases 
porphyry, from Scotland, Norway, Thuringia, 7 ant * 8 * 
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 Frau en- 
stein. Clay porphyry ; the same with the 
feldspar in several stages of decomposition ; 
with mica (the Saxum metalliferum of Baron 
Born, being the principal repository of gold and 
silver ores in Lower Hungary and Transylvania) : 
pitchstone porphyry ; porphyry balls ; porphyry 
breccia or Trummer-porphyry. — Porphyry slate. 
(Shelves 5 and 6.) Sienite: fragment of an case 
Egyptian idol, composed of much hornblende, 8, 
feldspar unequally distributed, and some mica: 
being the true signites of Pliny ; similar variety, 
but without mica ; with quartz (bia?ico e nero 
d'Egitto) : porphyritic sienite consisting chiefly 
of hornblende appearing to pass into hornblende 
slate, — Common hornblende rock. — Hornblende 
slate.— Greenstone. — Greenstone porphyry : por- 
Jzdo verde antico, or serpentino verde antico, 
as it is sometimes erroneously called. — Basalt, 
with 
