When I find this calcareous earth clofed within the
fiffure of any folid rock, and any part o f it mixed with
the mineral, while the remainder ferves for its matrix,
and that there is no other fimilar earth thereabouts, I
conclude that the aforefaid calcareous earth is formed by
the decompofition of. the rock which.it is in. I fay the
fame when I meet quartz mixed, and united with the
rock, for on breaking it, the ftone may be perceived
half decompofed, with fome part of clay in the centre-
Various ftala&ites are found in the excavations from this-
mine, which if well confidered, prove the origin and diurnal
formation o f the copper, and decompofition o f the
pack; one evidently perceives the mineral begins to be
diffolved, and fluid, or atleaft in a mucilaginous ftate, as-
its waves demonftrate its flowing in a very gentle mann
e r ; but when rain water has forced a paffage through
the crevices, and meets with that kind o f metallic drivel,
before it is thoroughly dry, or acquired a fuffieient com-
fiftence, it carries it forward, till it comes to fome cavity,
and there, drop by drop, it depofits it, and forms,
the ftala&ite, fometimes like a hollow reed, with bubbles
in it, occafioned by the air, but more frequently
folid, from the vifcolity of the matter. I obferved, by
analylis, that thofe ftala&ites o f the moft perfect green,
contain fix eighths o f pure copper, and two eighths of
calcareous earth ; they are fmooth, hard, and without
fmell, and do not decompofe either in the air or boiling
water ;
water ; but the green, blue, and yellow ftones, found
here, are the reverfe o f the ftaladlites, diflolving jn the
weakeft acid. I do not call thefe blue, and green ftones,
cryftals, becaufe they are not fo, though they have that
appearance, as is proved by experiments ; nor do I fay,
that the green is a malachite [a), it not being yet decided,
whether this is a green vitrifiable ftone.
In the cracks formed by the decompofition o f the
rocks, there is a great deal o f cinereous and yellow
clay, particularly where there is the moft mineral. Thefe
clays feem to precede the formation o f the white and yellow
calcareous earth, whofe quantity is always equal to
that of copper; fo that if one is abundant, the other is fo
Mkewife, and vice verfa. This yellow earth deceived me at
firft, having a notion that its mixture with blue, formed
the green ore, remembering to have feen the dyers co.m-
pofe their green colour, by an alfemblage o f yellow
and blue, and that the phyfical caufe of the greennefs
of leaves, proceeds from the mixture o f thofe two colours
; and finally, that there are feveral plants, indigo,
for example, whofe juices are deftroyed by fermentation,
and the blue colour remains in the fecuhe; but in
all this I was miftaken, as the blue ore does not. mix
with the green, they being o f different natures ; for
(a) Copper mixed with gyplum, or platter, Green. Is. found ar Órdal, m-Norway, and:
there called Malachites.— Cranfied, ie£t, cjccvi.
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