Ixxxii_ Historical Sketch of the Physical Sciences, 1818. 
Sica. ;..esstascuset %eree er 40°3 
Aludiina si .4.% eae Bt bute. 4-5 
_ Lithina .s..... BN Mskiss tet 7 4°3 
ONE OF O12 ions Baers haves 4°85 
Oxide of manganese........ 1°5 
Boracic. acid... «s,0 ee Fy 
Volatile matters..........0- 3°6 
“ 96°15 
_ 7. Foliated Pyrope, from Greenland.—This mineral has a 
deep blood colour. . Its lustre is not adamantine, like that of 
the pyrope, but common. It is composed of scaly distinct con- 
cretions. It is softer than pyrope. Its specific gravity 1s 3°634, 
ssaeording to the analysis of Pfaff, its constituents are as fol- 
OWS : 
TIENT pia yale i gm I Se 41°82 
Oxide of iron....... Spy ie 32°42 
CL glinegee atin sy abled ad Mare ite ie 17:82 
CEPA COI sc ss a's «cc og aid he 4:90 
Oxide of manganése....... 3°12 
Peme r fi REN 0:80 
100-88 
This approaches to Klaproth’s analysis of the pyrope. (Schweig- 
ger’s Journal, xxi. 236.) , 
8. Rutilite, from Arendahl—This mineral has a dark hair 
brown colour, passing into blackish brown. 
It is always crystallized ; but so confusedly that Professor 
Pfaff was unable to make out the form, though he thinks that 
it approaches most to a four-sided prism. 
he external surface is dull or slightly glimmering. The 
lustre of the longitudinal fracture is glistening, that of the cross 
fracture shining, and the kind of lustre approaches that of the 
diamond. . 
The principal fracture is foliated with a two-fold cleavage 
meeting under angles of 74° and 106°. The cross fracture is 
small conchoidal. 
It is composed of thick scaly distinct concretions. 
The fragments are quadrangular and sharp edged. 
It is translucent at the edges. 
It scratches glass, and even garnet. 
It is brittle and easily frangible. 
The colour of the powder is light brown. 
Specific gravity 3-879. 
Its constituents, according to the analysis of Professor Pfaff, 
are as follows : 
