30 Foreign Notices in Mineralogy, ¥c. 
{ conceive its primary form to be a right prism, whose base 
is an oblique-angled parallelogram of 59° and 120° 45”. 
But the crystals I have, are too imperfect to determine this 
point with precision, or to give the height of the prism. 
The sulphato-tri-carbonate consists of 
1 atom sulphate, 
ai: Ue aan. eat 
Specific gravity, 6.3 to 6.5. 
Hardness between sulphate of lead and cupreous sul- 
phate-carbonate. 
Colour of the rhomboidal crystals pale greenish, or yel- 
lowish, or brownish, or colourless and transparent, when 
very minute. 
The prismatic varieties are colourless, or of various 
shades of pale yellow. The rhomboids are acute, meas- 
uring 72° 30” and 107° 30”; and from not having found 
any other cleavage than one perpendicular to the axis of 
the crystal, | am induced to adopt this as the primary form. 
The principal modifications I have observed, are those 
which pass into the six-sided prism by the truncation of all 
the solid angles of the rhomboid, and those which produce 
more obtuse rhomboids, of which there are three or four. 
The natural planes of all except the most minute crystals 
are more or less rounded, and consequently afford imper- 
fect reflections. 7 
The cupreous sulphato-carbonate appears, from the sep- 
arate analysis of 
3.59 ers. to consist of — if the carb. of cop- 
5. ‘ (6atoms sulphate, > of lead, ) per be chemically 
5 “ (4° © -earbonate, combined, and not 
1.41 “ J3 “ carbonate of copper, \ accidental. 
Specific gravity about 6.4. 
Hardness between carbonate of lead and sulphato-tri- 
carbonate. 
Colour blue to dark greenish-blue. 
The primary form is a right prism, with either a rectan- 
gular or rhombic base. From the indication of joints par- 
allel to all the planes of the latter; and from not having ob- 
