OF THE MINERAL WORK.

which contain no gold but iron; which one may know from their lovely redness before cremation, which, upon cremation, turns into a dull redness, not bright and raw. But flints containing gold acquire a bright golden yellowness or a reddish color upon cremation, as if they were coated with gold, and that throughout the entire substance if they are broken into particles. And these give pure, refined gold; those others indeed give an extraction red like blood, but not gold, rather pure, refined, malleable iron of the best quality, not to be despised for chemical uses (and especially for cementing and exalting Luna silver); for gold is very rarely found in them; which must be well observed, lest you elicit iron instead of gold, and thus waste your effort and oil.

The best stones containing gold are those that are white, bright, and endowed here and there throughout their entire substance with green, red, yellow, blue, and brown spots and lines. Black flints are also found, from which fire is elicited by percussion, possessing gold and iron, which can be separated with profit, sometimes giving copious gold and iron separable by art, of which [I will speak] later.

The best flints are also those that retain their whiteness when burned, and are endowed with green, blue, and other veins. Nor are those to be despised which are not endowed with veins when burned, but with black spots.

As for the rocks or stones (Quartzen quartz and Hornstein chert), even if they are not altered in cremation, if volatile and spiritual gold was seen in them beforehand, by the force of separation they give their gold.