260 
THE GEOLOGIST. 
form large stalactites in caverns near a mine of copper-pyrites ; its 
colour is that of sulj)liate of copper, in the parts freshly broken (but 
with a green ochraceous tint on the exterior), whilst its crystalline 
form is that of sulphate of iron. On analysis, it turns out to be sul- 
phate of protoxide of iron, in whicli part of the oxide of iron is replaced 
by a corresponding quantity of oxide of copper. The figures obtained 
in M. Pisani's analysis are as follows : — 
Oxygen. Proportion. 
Oxide of copper . . . 15.5G . . 3.14) , 
Protoxide of iron . . 10.98 . . 2.44 f ' ' 
Sulphuric acid . . . 29.90 . . 17.94 . . 3 
Water 43.56 . . 38.72 . . 7 
100.00 
This composition leads to the formula : — | 0, SO^ -f 7 HO. 
We have also analysed this new mineral, and our figures coincide very 
closely with those above.* The formula arrived at is that of common 
green vitriol in which a certain quantity of iron is replaced by cop- 
per, the crystalline form having remained intact. It is probable that 
the natural production in question has been formed in the waters that 
filter tln-ough the beds of copper-pyrites, and that it could be formed 
artificially in the laboratory. 
Tungsten is a metal which has been hitherto little studied in a 
practical point of view. It appears destined, however, to operate a 
complete revolution in the manufacture of steel. It has been lately 
affirmed that an alloy formed of 80 per cent, of steel and 20 per cent, 
of tungsten, possesses a degree of hardness that has never yet been 
obtained in the manufacture of steel. This alloy works upon the 
latter, and can even cut it. Experiments have been made with this 
new composition at Vienna, Dresden, and at Neustadt-Ebertswalde, 
and considerable quantities of the alloy are being manufactured, it is 
said, in that part of the world. Many old tin-mines have been bought 
ujo with a view of extracting tungsten-ore, and considerable sums 
have been given for mines that had ceased to be worked long ago. 
* Another sample of the same suJistaiice analysed liy ourselves gave the follow- 
ing result : — 
Oxysren. Proportion. 
Oxide of copper . . . 1.5.8() ... 3.17 I . 
Protoxide of iron . . . 11.00. . . 2.44 ( ' ' ' 
Siili)huric acid .... 2N.0S , . . l(i.H5 ... 3 
Water 4.5.()« . . . 40.05 ... 7 
100.00 
Fonimla: -(Fe Cu) 'y4 7 It. 
In the resnlt giveit in the text there is evidently a slight excess of acid in pro- 
portion to the quantity of oxide foiuid. We have proposed for this mineral the 
name of VitrioUtc. — T. L. 1'. 
