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Title: Slags as Evidence for Copper Mining above Casaccia, Val Bregaglia (Central Alps)

Abstract

Slags from the remote Mota Farun locality above Casaccia (Val Bregaglia, Swiss Alps) have been analyzed with scanning electron microscopy, X-ray powder diffraction and microfocus synchrotron X-ray diffraction to determine mineralogical composition and microstructures. Non-magnetic slag samples are largely composed of euhedral and dendritic iron-rich olivine in a glassy matrix. Locally there are zones with globular inclusions rich in bornite ((Cu 5Fe)S 4) and locally metallic copper. Some regions display dendritic pentlandite ((Fe,Ni) 9S 8). Magnetic samples are mainly composed of fayalite (Fe 2SiO 4) and wüstite (FeO), with minor magnetite (Fe 3O 4). The mineralogical composition indicates that slags were the product of copper smelting. The slag compositions and morphologies are analogous to slags described from the Oberhalbstein (Graubünden, Switzerland) and the Trentino Alps (Italy) which are attributed to metallurgical exploitations of the Late Bronze Age. While the origin of the ore could not be determined, it may be related to ore deposits of chalcopyrite in greenschists and serpentinites in the vicinity, such as Alp Tgavretga (Septimer Pass) and Val Perossa (Val Bregaglia).

Authors:
ORCiD logo [1];  [2]; ORCiD logo [3];  [4];  [4]
  1. Univ. of California, Berkeley, CA (United States)
  2. Univ. of California, Berkeley, CA (United States); Xi’an Polytechnic Univ., Xi’an (China)
  3. Lawrence Berkeley National Lab. (LBNL), Berkeley, CA (United States)
  4. Independent Researcher (Switzerland)
Publication Date:
Research Org.:
Lawrence Berkeley National Lab. (LBNL), Berkeley, CA (United States)
Sponsoring Org.:
USDOE Office of Science (SC), Basic Energy Sciences (BES) (SC-22)
OSTI Identifier:
1529711
Alternate Identifier(s):
OSTI ID: 1564025
Grant/Contract Number:  
AC02-05CH11231; FG02-05ER15637
Resource Type:
Published Article
Journal Name:
Minerals
Additional Journal Information:
Journal Volume: 9; Journal Issue: 5; Journal ID: ISSN 2075-163X
Publisher:
MDPI
Country of Publication:
United States
Language:
English
Subject:
58 GEOSCIENCES; copper smelting; slags; Swiss alps; Casaccia; scanning electron microscopy; synchrotron X-rays

Citation Formats

Wenk, Hans -Rudolf, Yu, Rong, Tamura, Nobumichi, Bischoff, Duri, and Hunkeler, Walter. Slags as Evidence for Copper Mining above Casaccia, Val Bregaglia (Central Alps). United States: N. p., 2019. Web. doi:10.3390/min9050292.
Wenk, Hans -Rudolf, Yu, Rong, Tamura, Nobumichi, Bischoff, Duri, & Hunkeler, Walter. Slags as Evidence for Copper Mining above Casaccia, Val Bregaglia (Central Alps). United States. doi:10.3390/min9050292.
Wenk, Hans -Rudolf, Yu, Rong, Tamura, Nobumichi, Bischoff, Duri, and Hunkeler, Walter. Sun . "Slags as Evidence for Copper Mining above Casaccia, Val Bregaglia (Central Alps)". United States. doi:10.3390/min9050292.
@article{osti_1529711,
title = {Slags as Evidence for Copper Mining above Casaccia, Val Bregaglia (Central Alps)},
author = {Wenk, Hans -Rudolf and Yu, Rong and Tamura, Nobumichi and Bischoff, Duri and Hunkeler, Walter},
abstractNote = {Slags from the remote Mota Farun locality above Casaccia (Val Bregaglia, Swiss Alps) have been analyzed with scanning electron microscopy, X-ray powder diffraction and microfocus synchrotron X-ray diffraction to determine mineralogical composition and microstructures. Non-magnetic slag samples are largely composed of euhedral and dendritic iron-rich olivine in a glassy matrix. Locally there are zones with globular inclusions rich in bornite ((Cu5Fe)S4) and locally metallic copper. Some regions display dendritic pentlandite ((Fe,Ni)9S8). Magnetic samples are mainly composed of fayalite (Fe2SiO4) and wüstite (FeO), with minor magnetite (Fe3O4). The mineralogical composition indicates that slags were the product of copper smelting. The slag compositions and morphologies are analogous to slags described from the Oberhalbstein (Graubünden, Switzerland) and the Trentino Alps (Italy) which are attributed to metallurgical exploitations of the Late Bronze Age. While the origin of the ore could not be determined, it may be related to ore deposits of chalcopyrite in greenschists and serpentinites in the vicinity, such as Alp Tgavretga (Septimer Pass) and Val Perossa (Val Bregaglia).},
doi = {10.3390/min9050292},
journal = {Minerals},
number = 5,
volume = 9,
place = {United States},
year = {2019},
month = {5}
}

Journal Article:
Free Publicly Available Full Text
Publisher's Version of Record
DOI: 10.3390/min9050292

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