63 Capt. Bonnycastie on some of the 
This is a variety of the ochrey red oxide of iron, and 
might be made use of as a pigment, for which purpose it is in. 
deed sometimes sold at Marmora, at the rate of 25s, a ton, 
It may perhaps be rendered useful in the arts as its quali- 
ties are much the same as that brought from the gulf of 
Ormus. At Marmora it is abundant, and is used as a strong 
flux for the best ores. Its effects, in this way are repree 
sented as very great. 
N°. V.—Irregular mass ; apparently epidote and decompos- 
ing Felspar, Marmora, 
A green substance in distinct erystallizations intersecting. 
Fracture crystalline and laminated longitudinally ; cross frac- 
ture uneven, Powder, greenish gray, and harsh to the touch, 
Does not yield easily to the knife, and has a greenish gray 
streak, Opaque, or feebly transluent at the edges in thin 
laminee. Fresh fracture has alustrealmost metallic, shining 
and vitreous, or slightly resinous. Does not fuse easily, or 
scarcely at all, on charcoal, but in foreeps in a thin scale, it 
fuses with difficulty on the edges into a round black, dull, ena- 
mel, here and there. With borax, on platina wire, intume- 
sces, and yields a glass of a yellowish colour. Crystalline 
cleavage in two directions, longitawal and diagonal. 
There is also Tthink some hornbleade and mach iren fn 
this specimen. Rocks of this nature appear abnndant in the 
porphyritic sienite of Marmora. 
N°. VI.—Argillaceous carbonate of tron, Marmora. 
Yellowish brown, sparry looking masses, with an uneven 
fracture, and crystalline stracture which is lamellar, aad 
yesembles ealcspar, having a shining pearly lustre when turn- 
edto the light. Sweak very easily effected, and of a fight 
brownish yellow or yellowish white colour, Poder, rovgh 
and very red. ‘The powder when fine on the finger moves 
the needle faintly, Eflervesces in powder strongly ; when 
thrown juto nitric acid a bright red heavy powder sub- 
sides, and a metallic scum rises. Decrepitates on charcoal, 
aud falis into a metallic dull red powder, I 
