NNP

John Lorzeno’s recent paper, “Surface and Grading Issues in Honduran Provisional Eight Reales at the Tegucigalpa Mint: Insights from a Dual Analysis Method: XRF and SEM/EDS Analysis,” is now available on Newman Portal. XRF and SEM/EDS work differently and answer different questions – XRF is better for alloy identification, while SEM/EDS is more useful for analyzing microstructure, including specific particles or spots. Lorenzo’s objective here is to characterize the “signature” of genuine examples.

The paper demonstrates that Honduran provisional eight reales (1856–1861) were struck from highly inconsistent copper–lead alloys, with XRF showing most coins containing ~1–4% lead and occasional extreme cases up to ~14%, while SEM/EDS confirms that lead is immiscible in copper and segregates into discrete inclusions at grain boundaries; these inclusions act as weak points that fracture during striking, producing characteristic micro-cratering, pitting, and surface defects. The study concludes that many surface issues long attributed to environmental damage are actually intrinsic metallurgical and manufacturing flaws—stemming from poor planchet preparation, inadequate annealing, crude minting technology, and alloy instability—while higher lead levels exacerbate but do not solely cause defects such as lamination and fissuring. Overall, the combined XRF and SEM/EDS analysis reframes these coins as products of erratic metallurgy and primitive production methods, explaining both their degraded surfaces and frequent misgrading in numismatic practice.

Link to John Lorenzo papers on NNP: https://nnp.wustl.edu/library/booksbyauthor/524382