On the anomalous shapes of native copper crystals from the Michigan Copper Country

For over a century, the anomalous shapes of Michigan copper crystals from the Michigan Copper Country have been acknowledged. They are well known by mineral collectors and curated in museums from all around the world; still, their particular habits remain enigmatic. These natural crystals do not seem to follow crystal shape theories, based on the internal three-dimensional crystal structure. In this article, we offer a unique perspective on the formation of Michigan copper crystals. Firstly, we review the most common theories of crystal shapes. Then, taking into account the surface reconstructions induced by adsorbed oxygen, detected by ultra-high vacuum techniques, we present evidence of a strong correlation between these oxygen-induced surface reconstructions and the anomalous shapes. Finally, in order to understand why these shapes are not found in copper at other localities, oxygen dosing was performed using NanoSIMS on different natural copper crystals as a preliminary investigation. The higher oxygen content found in the Michigan copper crystal studied compared to others supports the influence of adsorbed oxygen on the anomalous crystal shapes. This result shows which mechanisms could modify crystal shapes and allow the development of strategies to monitor them, due to the presence of oxygen impurities. This new find is of great importance in shape-dependent catalysis, sensor characteristics, or other properties of material such as nanocrystals.

Creating a longitudinal, data-driven 3D model of change over time in a postindustrial landscape using GIS and CityEngine

Purpose The purpose of this paper is to create a longitudinal data-driven model of change over time in a postindustrial landscape, using the “Copper Country” of Michigan’s Upper Peninsula as a case study. The models resulting from this project will support the heritage management and public education goals of the contemporary communities and Keweenaw National Historical Park that administer this nationally significant mining region through accessible, engaging, and interpretable digital heritage. Design/methodology/approach The paper applies Esri’s CityEngine procedural modeling software to an existing historical big data set. The Copper Country Historical Spatial Data Infrastructure, previously created by the HESA lab, contains over 120,000 spatiotemporally specific building footprints and other built environment variables. This project constructed a pair of 3D digital landscapes comparing the built environments of 1917 and 1949, reflecting the formal and functional evolution of several of the most important copper mining, milling, and smelting districts of Michigan’s Keweenaw Peninsula. Findings This research discovered that CityEngine, while intended for rapid 3D modeling of the contemporary urban landscape, was sufficiently robust and flexible to be applied to modeling serial historic industrial landscapes. While this novel application required some additional coding and finish work, by harnessing this software to existing big data sets, 48,000 individual buildings were rapidly visualized using several key variables. Originality/value This paper presents a new and useful application of an existing 3D modeling software, helping to further illuminate and inform the management and conservation of the rich heritage of this still-evolving postindustrial landscape.