MINERAL from GREENLAND. “393 
3- A flat prifm, with the acute angle of 63° replaced by 
one plane, and terminated by an acumination, having 
three principal facettes fet on the larger lateral planes, with 
which the centre one meafures 125° and 55°. Ofthis °* 
fpecimen, an engraving is given in the annexed Plate, 
Fig. 2. 
SPECIFIC gravity, according to my experiments, 3.533. The 
fpecimen appears to be nearly, though not abfolutely, pure. 
This fubftance, however, is fo very much mixed with mica, 
that no reliance can be placed on any of the trials which have 
been made. Count Bournon, furprifed at the low fpecific gra- 
vity noted by Mr Ain, which was 3.480,broke down one of 
the fpecimens which had been fent him, in order to procure 
the fubftance in the pureft ftate poffible, and the refult of four 
experiments was as follows, 4.001 
3-797 
3-654 
SaEL ORS ; 
‘In a fubfequent experiment of Mr Atian’s, he found it 3.665. 
From thefe it appears, that the fubftance is not in a pure ftate. 
Its colour is fo entirely the fame with the mica, with which it 
is accompanied, that it is only by mechanical attrition that 
they can be feparated. 
Co our, brownifh-black. 
- External luftre, dull; internal, fhining and refinous, flight- 
ly inclining to metallic. 
FractTuRE, {mall conchoidal. 
FRAGMENTS, indeterminate, fharp-edged. 
- OPAKE. 
SEMI-HARD in a high degree. Does not feratch quartz nor 
felfpar, but {eratches hornblende and crown-glafs, 
BRITTLE. 
EAsILy 
