1817.) during the Year 1816. 71 
xv. 377. It occurs usually crystallized in four-sided rectangular 
risms, whose bases are squares. They are always so low that they 
elong to the kind denominated by the Germans éable; that is, the 
sides of the prism are smaller than its bases. ‘They are commonl 
small, never exceeding 44 lines in length, and 61 in breadth. They 
are entangled in each other, and the intervals between them are 
usually filled up with calcareous spar. They have a triple cleavage, 
two of which can be readily distinguished; but the third with 
difficulty. 
The specific gravity is 2:98. It is moderately easily frangible, 
and semihard in a high degree, scratching glass, but not striking 
fire with steel. 
The fracture is sometimes uneven, sometimes fine splintery. 
Lustre weakly glimmering, or almost dull. The kind of lustre js 
intermediate between vitreous and resinous. 
It has no very decided colour ; but its principal colour is interme- 
diate between olive and leek green; and passes on the one side 
through dark bluish-grey to bluish-black, and on the other to dark 
oil-green or liver-brown. 
It is usually only translucent on the edges, sometimes quite opake, 
and only the very small crystals are entirely translucent. The 
crystals have somewhat of a resinous feel. The powder feels 
meagre. 
Before the blow-pipe it melts with difficulty into a yellowish- 
green bead, which has some degree of transparency. When the 
flame is long continued, it becomes black. 
According to the analysis of Fuchs its constituents are, 
BMC Porites a0. 413-4) 3 kage dre alas oe 29°64 
MMU SSMU ie ren 5 ce. «cosmid stato 24°80 
Mar a ts dina egertes 9 ons ce a eet 35°30 
PPROR ON We oid cain sweeten acts 6°56 
TAIN ahs bs cetite a aie avait he aiets fete eee ome 3°30 
99:60 
7. Carlo-silicate of Copper—In the Annals, vii. 321, I have 
described a new species of copper ore, which Mr. Mawe received 
from Mexico, and gave likewise an analysis of it. An anonymous 
correspondent has rendered it probable that it is a combination of 
carbonate of copper and silicate of copper. He hasshown likewise 
that dioptase is a combination of hydrate of copper and silicate of 
copper. (Annals, viii. 151.) The symbols for these two species of 
copper ore will be as follows :— 
Carbo-silicate........0.008. Cu C + Cu S' 
Hydro-silicate ............ Cu H*+ Cu S° 
8. Aachen Mass of Iron—In the Annals, vi. 53, I inserted a 
short historical account of the celebrated Aachen mass of iron, 
Since that time a particular description of this mass has been pub- 
lished by Berg-Commissiir Noeggerath, together with an elaborate 
chemical analysis of it by Dr. J. P. J. Monheim. (Schweigger’s 
Journal, xvi, 196, July, 1816.) 
