I have spoken of shafts, tunnels, and drifts.
I will now speak of the
indications given by the canales, by the materials which are dug out, and by
the rocks. These indications, as also many others which I will explain, are
to a great extent identical in venae dilatatae and venae cumulatae with venae
profundae.
indications given by the canales, by the materials which are dug out, and by
the rocks. These indications, as also many others which I will explain, are
to a great extent identical in venae dilatatae and venae cumulatae with venae
profundae.
When a stringer junctions with a main vein and causes a swelling, a
shaft should be sunk at the junction. But when we find the stringer inter
secting the main vein crosswise or obliquely, if it descends vertically down
to the depths of the earth, a second shaft should be sunk to the point where
the stringer cuts the main vein; but if the stringer cuts it obliquely the
shaft should be two or three fathoms back, in order that the junction may
be pierced lower down. At such junctions lies the best hope of finding the
ore for the sake of which we explore the ground, and if ore has already been
found, it is usually found in much greater abundance at that spot. Again,
if several stringers descend into the earth, the miner, in order to pierce
through the point of contact, should sink the shaft in the midst of these
stringers, or else calculate on the most prominent one.
shaft should be sunk at the junction. But when we find the stringer inter
secting the main vein crosswise or obliquely, if it descends vertically down
to the depths of the earth, a second shaft should be sunk to the point where
the stringer cuts the main vein; but if the stringer cuts it obliquely the
shaft should be two or three fathoms back, in order that the junction may
be pierced lower down. At such junctions lies the best hope of finding the
ore for the sake of which we explore the ground, and if ore has already been
found, it is usually found in much greater abundance at that spot. Again,
if several stringers descend into the earth, the miner, in order to pierce
through the point of contact, should sink the shaft in the midst of these
stringers, or else calculate on the most prominent one.
Since an inclined vein often lies near a vertical vein, it is advisable
to sink a shaft at the spot where a stringer or cross-vein cuts them both;
or where a vena dilatata or a stringer dilatata passes through, for minerals
are usually found there. In the same way we have a good prospect of finding
metal at the point where an inclined vein joins a vertical one; this is why
miners cross-cut the hangingwall or footwall of a main vein, and in these
openings seek for a vein which may junction with the principal vein a few
fathoms below. Nay, further, these same miners, if no stringer or cross
vein intersects the main vein so that they can follow it in their workings,
even cross-cut through the solid rock of the hangingwall or footwall. These
cross-cuts are likewise called “κρυπταί,” whether the beginning of the
opening which has to be undertaken is made from a tunnel or from a drift.
Miners have some hope when only a cross vein cuts a main vein. Further,
if a vein which cuts the main vein obliquely does not appear anywhere
beyond it, it is advisable to dig into that side of the main vein toward which
the oblique vein inclines, whether the right or left side, that we may ascer
tain if the main vein has absorbed it; if after cross-cutting six fathoms it
is not found, it is advisable to dig on the other side of the main vein, that
we may know for certain whether it has carried it forward. The owners
of a main vein can often dig no less profitably on that side where the vein
which cuts the main vein again appears, than where it first cuts it; the
owners of the intersecting vein, when that is found again, recover their title,
which had in a measure been lost.
to sink a shaft at the spot where a stringer or cross-vein cuts them both;
or where a vena dilatata or a stringer dilatata passes through, for minerals
are usually found there. In the same way we have a good prospect of finding
metal at the point where an inclined vein joins a vertical one; this is why
miners cross-cut the hangingwall or footwall of a main vein, and in these
openings seek for a vein which may junction with the principal vein a few
fathoms below. Nay, further, these same miners, if no stringer or cross
vein intersects the main vein so that they can follow it in their workings,
even cross-cut through the solid rock of the hangingwall or footwall. These
cross-cuts are likewise called “κρυπταί,” whether the beginning of the
opening which has to be undertaken is made from a tunnel or from a drift.
Miners have some hope when only a cross vein cuts a main vein. Further,
if a vein which cuts the main vein obliquely does not appear anywhere
beyond it, it is advisable to dig into that side of the main vein toward which
the oblique vein inclines, whether the right or left side, that we may ascer
tain if the main vein has absorbed it; if after cross-cutting six fathoms it
is not found, it is advisable to dig on the other side of the main vein, that
we may know for certain whether it has carried it forward. The owners
of a main vein can often dig no less profitably on that side where the vein
which cuts the main vein again appears, than where it first cuts it; the
owners of the intersecting vein, when that is found again, recover their title,
which had in a measure been lost.
The common miners look favourably upon the stringers which come
from the north and join the main vein; on the other hand, they look
unfavourably upon those which come from the south, and say that these do
much harm to the main vein, while the former improve it. But I think
that miners should not neglect either of them: as I showed in Book III,
experience does not confirm those who hold this opinion about veins, so now
from the north and join the main vein; on the other hand, they look
unfavourably upon those which come from the south, and say that these do
much harm to the main vein, while the former improve it. But I think
that miners should not neglect either of them: as I showed in Book III,
experience does not confirm those who hold this opinion about veins, so now
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