So when Chrysocoll is found mixt with the Azure, or the Azure with Chrysocoll, and Auripigment, for the most part they signifie an excellent and rich Minerall.
Where stones, or earth are found of an Iron colour, they doe certainly betoken an Iron Mine.
You must note, that sometimes it comes to passe, that the Archeius of the earth doth by some secret passage cast up some Metall from the more inward part of the earth. And that is a good signe.
Miners therefore must not bee discouraged when they see such certaine signes, and hope of some excellent Mine lying under. And if thin leaves of Metalls, like Talke, do adhere to rocks, or stones, that is a most sure sign.
What Coruscations signifie in Mines.
Now concerning Coruscations they must bee diligently, and studiously observed, for, they are most certain signes of Metalls lying hid under them, as also of the same extent, and same kind. Where yet wee must note, that those Metalls are not yet come to perfection, but are as yet in their first being. And whither soever the Coruscation reacheth, so far also reacheth the course of Metalls, &c.
Coruscations are of three colours.
Moreover you must know, that Coruscation is of a threefold colour, as White, Yellow, and Red, whereby all Metalls are discovered to us. For a white Coruscation signifies white Metalls, as Tinne, Lead, Silver, &c. a red Coruscation signifies red Metalls, as Copper, and Iron, &c. a yellow Coruscation signifies golden Metalls.
Add moreover, that a thin, and subtil Coruscation is the best signe.