Agricola, Georgius
,
De re metallica
,
1912/1950
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<
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>I have spoken of shafts, tunnels, and drifts. </
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<
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>I will now speak of the
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indications given by the
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canales,
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by the materials which are dug out, and by
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the rocks. </
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<
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>These indications, as also many others which I will explain, are
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to a great extent identical in
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venae dilatatae
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and
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venae cumulatae
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with
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venae
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profundae.
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<
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>When a stringer junctions with a main vein and causes a swelling, a
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shaft should be sunk at the junction. </
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>
<
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>But when we find the stringer inter
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secting the main vein crosswise or obliquely, if it descends vertically down
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to the depths of the earth, a second shaft should be sunk to the point where
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the stringer cuts the main vein; but if the stringer cuts it obliquely the
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shaft should be two or three fathoms back, in order that the junction may
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be pierced lower down. </
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<
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>At such junctions lies the best hope of finding the
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ore for the sake of which we explore the ground, and if ore has already been
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found, it is usually found in much greater abundance at that spot. </
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>
<
s
>Again,
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if several stringers descend into the earth, the miner, in order to pierce
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through the point of contact, should sink the shaft in the midst of these
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stringers, or else calculate on the most prominent one.</
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>
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<
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>Since an inclined vein often lies near a vertical vein, it is advisable
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to sink a shaft at the spot where a stringer or cross-vein cuts them both;
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or where a
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vena dilatata
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or a stringer
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dilatata
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passes through, for minerals
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are usually found there. </
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>
<
s
>In the same way we have a good prospect of finding
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metal at the point where an inclined vein joins a vertical one; this is why
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miners cross-cut the hangingwall or footwall of a main vein, and in these
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openings seek for a vein which may junction with the principal vein a few
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fathoms below. </
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>
<
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>Nay, further, these same miners, if no stringer or cross
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vein intersects the main vein so that they can follow it in their workings,
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even cross-cut through the solid rock of the hangingwall or footwall. </
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>
<
s
>These
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cross-cuts are likewise called “
<
foreign
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="
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">κρυπταί,</
foreign
>
” whether the beginning of the
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opening which has to be undertaken is made from a tunnel or from a drift.
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</
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>
<
s
>Miners have some hope when only a cross vein cuts a main vein. </
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>
<
s
>Further,
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if a vein which cuts the main vein obliquely does not appear anywhere
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beyond it, it is advisable to dig into that side of the main vein toward which
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the oblique vein inclines, whether the right or left side, that we may ascer
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tain if the main vein has absorbed it; if after cross-cutting six fathoms it
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is not found, it is advisable to dig on the other side of the main vein, that
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we may know for certain whether it has carried it forward. </
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>
<
s
>The owners
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of a main vein can often dig no less profitably on that side where the vein
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which cuts the main vein again appears, than where it first cuts it; the
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owners of the intersecting vein, when that is found again, recover their title,
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which had in a measure been lost.</
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>
</
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>
<
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type
="
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">
<
s
>The common miners look favourably upon the stringers which come
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from the north and join the main vein; on the other hand, they look
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/>
unfavourably upon those which come from the south, and say that these do
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much harm to the main vein, while the former improve it. </
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>
<
s
>But I think
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that miners should not neglect either of them: as I showed in Book III,
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experience does not confirm those who hold this opinion about veins, so now </
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>
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