1which the tin itself is made, and a
material they dig up resembling litharge;
of iron, iron rust. Gold and copper are equally indicated by chrysocolla and
azure; silver and lead, by the lead. But, though miners rightly
call bismuth “the roof of silver,” and though copper pyrites is the common
parent of vitriol and melantería, still these sometimes have their own
peculiar minerals, just as have orpiment and stibium.
of iron, iron rust. Gold and copper are equally indicated by chrysocolla and
azure; silver and lead, by the lead. But, though miners rightly
call bismuth “the roof of silver,” and though copper pyrites is the common
parent of vitriol and melantería, still these sometimes have their own
peculiar minerals, just as have orpiment and stibium.
Now, just as certain vein materials give miners a favourable indication,
so also do the rocks through which the canales of the veins wind their
way, for sand discovered in a mine is reckoned among the good indications,
especially if it is very fine. In the same way schist, when it is of a
bluish or blackish colour, and also limestone, of whatever colour it may be, is
a good sign for a silver vein. There is a rock of another kind that is a good sign;
in it are scattered tiny black stones from which tin is smelted; especially when
the whole space between the veins is composed of this kind of rock.
Very often indeed, this good kind of rock in conjunction with valuable
stringers contains within its folds the canales of mineral bearing veins: if
it descends vertically into the earth, the benefit belongs to that mine in
which it is seen first of all; if inclined, it benefits the other neighbouring
mines12. As a result the miner who is not ignorant of geometry can calculate
from the other mines the depth at which the canales of a vein bearing rich
metal will wind its way through the rock into his mine. So much for these
matters.
so also do the rocks through which the canales of the veins wind their
way, for sand discovered in a mine is reckoned among the good indications,
especially if it is very fine. In the same way schist, when it is of a
bluish or blackish colour, and also limestone, of whatever colour it may be, is
a good sign for a silver vein. There is a rock of another kind that is a good sign;
in it are scattered tiny black stones from which tin is smelted; especially when
the whole space between the veins is composed of this kind of rock.
Very often indeed, this good kind of rock in conjunction with valuable
stringers contains within its folds the canales of mineral bearing veins: if
it descends vertically into the earth, the benefit belongs to that mine in
which it is seen first of all; if inclined, it benefits the other neighbouring
mines12. As a result the miner who is not ignorant of geometry can calculate
from the other mines the depth at which the canales of a vein bearing rich
metal will wind its way through the rock into his mine. So much for these
matters.
I now come to the mode of working, which is varied and complex, for in
some places they dig crumbling ore, in others hard ore, in others a harder
ore, and in others the hardest kind of ore. In the same way, in some places
the hangingwall rock is soft and fragile, in others hard, in others harder, and
in still others of the hardest sort. I call that ore “crumbling” which is com
posed of earth, and of soft solidified juices; that ore “hard” which is composed
of metallic minerals and moderately hard stones, such as for the most part
are those which easily melt in a fire of the first and second orders, like lead
and similar materials. I call that ore “harder” when with those I have already
mentioned are combined various sorts of quartz, or stones which easily melt
in fire of the third degree, or pyrites, or cadmia, or very hard marble. I call
that ore hardest, which is composed throughout the whole vein of these hard
stones and compounds. The hanging or footwalls of a vein are hard, when
composed of rock in which there are few stringers or seams; harder, in
which they are fewer; hardest, in which they are fewest or none at all.
When these are absent, the rock is quite devoid of water which softens
it. But the hardest rock of the hanging or footwall, however, is seldom as
hard as the harder class of ore.
some places they dig crumbling ore, in others hard ore, in others a harder
ore, and in others the hardest kind of ore. In the same way, in some places
the hangingwall rock is soft and fragile, in others hard, in others harder, and
in still others of the hardest sort. I call that ore “crumbling” which is com
posed of earth, and of soft solidified juices; that ore “hard” which is composed
of metallic minerals and moderately hard stones, such as for the most part
are those which easily melt in a fire of the first and second orders, like lead
and similar materials. I call that ore “harder” when with those I have already
mentioned are combined various sorts of quartz, or stones which easily melt
in fire of the third degree, or pyrites, or cadmia, or very hard marble. I call
that ore hardest, which is composed throughout the whole vein of these hard
stones and compounds. The hanging or footwalls of a vein are hard, when
composed of rock in which there are few stringers or seams; harder, in
which they are fewer; hardest, in which they are fewest or none at all.
When these are absent, the rock is quite devoid of water which softens
it. But the hardest rock of the hanging or footwall, however, is seldom as
hard as the harder class of ore.
Miners dig out crumbling ore with the pick alone.
When the metal
has not yet shown itself, they do not discriminate between the hangingwall
and the veins; when it has once been found, they work with the utmost care.
For first of all they tear away the hangingwall rock separately from the vein,
afterward with a pick they dislodge the crumbling vein from the footwall
has not yet shown itself, they do not discriminate between the hangingwall
and the veins; when it has once been found, they work with the utmost care.
For first of all they tear away the hangingwall rock separately from the vein,
afterward with a pick they dislodge the crumbling vein from the footwall