Mineralogy. lxxit- 
Richard Phillips to an ore of copper found in the mines of Dol- 
coath, Cook’s Kitchen, and Tincroft, near Redruth, and in Huel 
Virgin, Huel Unity, and Huel Jewel, near St. Die. It has been 
hitherto considered as a variety of grey copper ore (fahlerz) ; 
but its specific gravity is inferior, its hardness greater, and it has 
never been observed crystallized in tetrahedrons. 
Its colour varies from lead-grey to iron-black. 
It is usually crystallized in rhomboidal dodecahedrons, either 
perfect, or variously modified. Some of the modifications are 
figured by Mr. William Phillips, in the Quarterly Journal, 
vu. 97. i 
Crystals externally sometimes tin-white and splendent ; some- 
times lead-grey, and glistening ; sometimes iron-black, and dull? 
Lustre of the fragments from shining to glistening : metallic.» / 
Fracture imperfectly foliated, and uneven, with the appearance: 
“a pore joints parallel to the faces of the rhomboidal dodeca-. 
edron. 
Harder than vitreous copper or grey copper ore, both of whick. 
it scratches. be 
Brittle. Specific gravity 4°375.. Powder reddish-grey. 
Before the blow-pipe on charcoal, it burns first with a blue 
flame, and slight decrepitation ; to which succeed copious arse- 
nical vapours, leaving a greyish-black scoria which affects the: 
magnetic needle. bY cad 
Its constituents, according to the analysis of Mr. Richard 
Phillips, are as follows : a 
PTE: A i IR al I RIG | 
Tron eeeeeesevp ees ee eave ee ee 9-96 
. 
qoppee b samcice as 4 Psleginie Es 
Sulp or . eeeeeeeoeoeaev ee ee ee 98°74 
PERCING  . 'n.5\9. 0, mssunhncall 6 vigilant, MAREE, 
100-16 
—(See Quarterly Journal, vii. 95.) 
I have a single specimen of this ore, which I brought from: 
Cornwall (I think from the united mines near Redruth). I con-: 
sidered it as probably a variety of grey-copper ore, though it: 
differed from it materially in lustre, golour, and hardness ; but: 
from Mr. Phillips’s description, there seems no reason to doubt. 
that it constitutes a peculiar species. As to the composition of. 
the sulphuretted ores of copper, the subject is at present involved . 
in impenetrable obscurity, in which it must remain till some che-- 
mist be fortunate enough to meet with specimens of eath species: 
perfectly free from all foreign matter. é; 
Il, NEW ANALYSES OF MINERALS. ; 
1, Tourmaline —In the number of Gilbert’s Annalen der 
Physik for April, 1818, Lampadius announces that he and. Breit- 
