| The metal extraction by ore leaching (mostly copper) was about 1,000 years BC. known in the Mediterranean, but there are also barely no written records. The in the Middle Ages and in the following Renaissance well-known different procedures were first described in detail by Georg Agricola 1556 in hi ... moreThe metal extraction by ore leaching (mostly copper) was about 1,000 years BC. known in the Mediterranean, but there are also barely no written records. The in the Middle Ages and in the following Renaissance well-known different procedures were first described in detail by Georg Agricola 1556 in his book "De Re Metallica Libri XII". A contribution by Peter Seroka |
| We do not thumble stones to get smooth and even things that look like the tumbled stones in the esoteric shops, but to discover the secret of the stone. We have thumbled stones in the spirator for years and have documented our experiences with stones, machinery, abrasives and polishing techniques. O ... moreWe do not thumble stones to get smooth and even things that look like the tumbled stones in the esoteric shops, but to discover the secret of the stone. We have thumbled stones in the spirator for years and have documented our experiences with stones, machinery, abrasives and polishing techniques. Our experience will help you to avoid errors and run approach to the subject. |