| 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 |
| Unser Einsteigerguide ist eine kleine Anleitung Dir selbst zu helfen oder richtig nach Hilfe zu fragen. Die passenden Informationen helfen Dir schnell eine Antwort zu erhalten und dem Fachmann Dir Auskunft zu erteilen. Nehme Dir bitte die 10 Minuten Zeit um den Guide durchzulesen. Ein lesenswerter B ... moreUnser Einsteigerguide ist eine kleine Anleitung Dir selbst zu helfen oder richtig nach Hilfe zu fragen. Die passenden Informationen helfen Dir schnell eine Antwort zu erhalten und dem Fachmann Dir Auskunft zu erteilen. Nehme Dir bitte die 10 Minuten Zeit um den Guide durchzulesen. Ein lesenswerter Beitrag der Sammlergemeinschaft |
| Actually, this is a picturesque place in a well-kept forest. Nevertheless, in the past, evil itself is said to have preached to the damned here from a large, solitary, towering rock spur. Today, the term Devil's Pulpit inspires one to play with associations, as do the drawings of agates found here. ... moreActually, this is a picturesque place in a well-kept forest. Nevertheless, in the past, evil itself is said to have preached to the damned here from a large, solitary, towering rock spur. Today, the term Devil's Pulpit inspires one to play with associations, as do the drawings of agates found here. Their fantastic outlines, coupled with the unusual shape of the secondary rock, evoke images in the viewer that he would not have suspected in a stone. And on the devil's pulpit no longer an evil demon is waiting for the agate collector, but other executive powers threatening with purgatory... a contribution by Klaus Schäfer and others (in german) |
| Aragonite is a calcium carbonate, chemically identical with calcite. The mineral calcite, however, differs from Aragonite due to its internal crystal structure. While the crystal system of calcite is trigonal, the system of aragonite is rhombic. Dense masses of small aragonite crystals are difficul ... moreAragonite is a calcium carbonate, chemically identical with calcite. The mineral calcite, however, differs from Aragonite due to its internal crystal structure. While the crystal system of calcite is trigonal, the system of aragonite is rhombic. Dense masses of small aragonite crystals are difficult to distinguish from calcite, but they are larger, they show a distinct habit. A lot of chapters in this portrait will give you much more details about this interesting mineral. Written and investigated by Peter Seroka. (Article in german) |
| The study of twins starts due to the very first beginnings of crystallography as a science. Not negligible for this reason, the idea or the concept of a twin crystal are often associated with a macroscopic building. Modern studies at the nano scale have shown that the formation of twins can occur at ... moreThe study of twins starts due to the very first beginnings of crystallography as a science. Not negligible for this reason, the idea or the concept of a twin crystal are often associated with a macroscopic building. Modern studies at the nano scale have shown that the formation of twins can occur at a very early stage of crystal growing. Based on these findings, it does beg the request to reconsider the formation mechanisms, and adjacency to the newly different categories. (Text in german) |