An Investigation of the Antimony-Containing Minerals used by the Romans to Prepare Opaque Colored Glasses
- PDF / 1,401,752 Bytes
- 12 Pages / 416.88 x 649.62 pts Page_size
- 68 Downloads / 227 Views
the Roman empire [6,7]. Bindheimite can be found in the Tuscany and Lombardia regions of Italy, in the Cornwall region of Britain (at St. Endellion), in the Sierra Almagrera and Sierra Cabrera regions of Spain, and on the Greek island of Siphnos [8-13]. Bindheimite forms as an oxidation product of antimonial lead ores, and its European deposits are often only thin weathering crusts. The only substantial deposit of bindheimite within the Roman empire occurs at Djebel Slata, Tunisia. Although this region of North Africa was crossed by many Roman trade routes, there is no reference to either the use or trade of this mineral in the classical literature
[14]. Stibnite (Sb2S 3) is a gray-black, metallic antimony sulfide. This mineral is quite common and occurs in significant quantities in deposits in the Tuscany region of Italy, Central Europe, the Near East, and the Iberian peninsula [15-17]. Dionysius Periegetes makes reference to a stibnite trade from East Africa to India in the I" century AD [18]. Pliny the Elder (23 AD - 79 AD) gives a description of stibnite in his Natural Histolry (XXXIII, 101): "In the same mines as silver there is found what is properly to be described as a stone, made of white and shiny but not transparent froth; several names are used for it, stimi, stibi, alabastrum, and sometimes larbasis." [19]. Pliny also describes the roasting of stibnite to prepare a white, mixed antimony oxide powder (Sb 2 0 3 , Sb 20 4) for pharmaceutical purposes [Natural Histry (XXXIII, 103-104)] [20]. He does not mention the use of stibnite or its oxidation products in glassmaking. Antimonial litharge (Sb-PbO) is an antimony-containing metallurgical byproduct that was unwittingly produced during the Roman period. Litharge is a yellow polymorph of lead oxide that was produced in antiquity as a byproduct of cupellation, a metallurgical process first developed around 2500 BC to win silver and gold from base metals [21]. The cupellation of the antimonial silver ores mined by the Romans (discussed below) resulted in the production of large quantities of litharge contaminated with antimony. The use of an antimonial litharge flux by Roman glassmakers would have resulted in the fortuitous introduction of antimony into Roman glass batches. Pliny's reference to stibnite being obtained from silver mines (Natural HistQory XXXIII, 101) indicates that the silver ores mined in the Roman period were antimonial [22]. Two important silver ores worked by the Romans were argentiferous galena and the jarositic silver ores. The silver ore deposits exploited by the Romans in Spain also contained dry silver ores and complex lead-antimony-silver sulfides [23,24]. Argentiferous galena (PbS) was exploited by the Romans in the Cornwall and Somerset regions of Britain and in Spain near Cartagena (Nova Cartago) [23,25,26]. Silver occurs in argentiferous galena substituted into the PbS lattice, as a complex sulfide mineral inclusion, or as native metal precipitated at the grain boundaries [27,28]. The solubility of silver in galena is much incr
Data Loading...
