348 Professor Haussmann on Metallurgic Crystallography. 
plete in the central part. The colour of the crystal is olivaceous, 
with various degrees of lustre, passing from an olive into a 
waxen hue. The crystals are sometimes transparent, sometimes 
semitransparent, and the lateral planes possess a vitreous lustre, 
and the terminal planes have a pearly lustre. 
I have ascertained, by a sufficiently accurate measurement, 
that the crystals are regular hexagonal prisms. When it was 
difficult to take a direct measurement, on account of the small- 
ness of the crystals, I was assisted by the following experiment : 
I impressed the terminal planes upon paper, covered over 
with the smoke of a candle, the angles of which delicate impres- 
sion I could subject to a more accurate measurement. Besides 
this, I observed a second variety, where the terminal edges of 
the regular hexagonal prism are truncated; but I could not 
ascertain the angles of the truncations, on account of the small- 
ness of the inclined planes. 
h. Copper-Mica. — Copper-mica is an interesting production, 
and merits particular attention. It is a very disagreeable guest 
in the copper found eries of the Hartz, where it has been long 
known. It consists of very thin plates, having a middle colour 
between gold and copper, and a metallic lustre. When more 
accurately examined, the plates appear for the most part to have 
a regular hexagonal tabular form, and the crystals attain the 
diameter of a few lines. 
Stromeyer, by a laborious chemical analysis of copper^mica, 
Lias illustrated its probable nature ; a hundred parts contain 
54.25 Oxide of Copper 
39.81 White Oxide of Antimony 
4.05 Oxide of Lead 
0.16 Oxide of Silver 
0.07 Oxide of Iron 
1.58 Silica, having a trace of Alumina 
0.08 Sulphur 
100 . 
c. Crystalline Vitreous Scorice.-— -The substances produced in 
founderies, but especially scoriae, have been hitherto regarded 
with less attention than their real merit demands, from the mis- 
taken practice of throwing away the residue, as in a great mea- 
sure useless, because, on being analysed, they are said to be of 
no advantage in metallurgical processes. But this cannot, 
