TY - JOUR
T1 - Evidence for Early Bronze Age tin ore processing
AU - Laughlin, Gary J.
AU - Todd, Judith A.
N1 - Funding Information:
This research was supported by Professor Aslihan Yener of the Oriental Institute, University of Chicago, who provided all the archaeological materials for the study, the McCrone Research Institute, and the Illinois Institute of Technology. The authors gratefully acknowledge their support.
PY - 2000/10
Y1 - 2000/10
N2 - Recent discoveries related to ores from Kestel Mine in the Taurus Mountains of Turkey show how prehistoric miners used the magnetic properties of the black iron oxide to accomplish the difficult separation of cassiterite (tin oxide) from low-grade cassiterite ores. Excavations at the site of Göltepe, dating to the third millenium BC, have yielded hematite ore nodules containing a few percent, or less, of cassiterite and a sequence of processed, ground, and separated minerals. Laboratory experiments showed that reduction at temperatures as low as 700-850°C converted hematite to the black magnetic oxide, which could be much more easily crushed than the hematite ore. On grinding and panning this material, the magnetic oxide clumped together effectively to yield almost complete separation of the cassiterite grains, a separation which, without automatic magnetic clumping, would be extremely difficult to accomplish due to the similar densities of cassiterite and magnetite minerals. The deliberate production of magnetic oxide may explain the shallow crucible bowl furnaces, the vast quantities of stone grinding tools, the large amount of residual magnetite at the site, and the fine particle sizes (which were necessary for the magnetic separation). These findings establish Kestel/Göltepe as a viable cassiterite (ore) production site.
AB - Recent discoveries related to ores from Kestel Mine in the Taurus Mountains of Turkey show how prehistoric miners used the magnetic properties of the black iron oxide to accomplish the difficult separation of cassiterite (tin oxide) from low-grade cassiterite ores. Excavations at the site of Göltepe, dating to the third millenium BC, have yielded hematite ore nodules containing a few percent, or less, of cassiterite and a sequence of processed, ground, and separated minerals. Laboratory experiments showed that reduction at temperatures as low as 700-850°C converted hematite to the black magnetic oxide, which could be much more easily crushed than the hematite ore. On grinding and panning this material, the magnetic oxide clumped together effectively to yield almost complete separation of the cassiterite grains, a separation which, without automatic magnetic clumping, would be extremely difficult to accomplish due to the similar densities of cassiterite and magnetite minerals. The deliberate production of magnetic oxide may explain the shallow crucible bowl furnaces, the vast quantities of stone grinding tools, the large amount of residual magnetite at the site, and the fine particle sizes (which were necessary for the magnetic separation). These findings establish Kestel/Göltepe as a viable cassiterite (ore) production site.
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U2 - 10.1016/S1044-5803(00)00111-X
DO - 10.1016/S1044-5803(00)00111-X
M3 - Article
AN - SCOPUS:0034289353
SN - 1044-5803
VL - 45
SP - 269
EP - 273
JO - Materials Characterization
JF - Materials Characterization
IS - 4-5
ER -