Newman Numismatic Portal at Washington University in St. Louis | Comprehensive Research & Reference for U.S. Coinage

Lorenzo, John

Past President of Northern Valley Coin Club (NJ), past Secretary of C4. Author of articles in three of the American Numismatic Society's Coinage of the Americas Conference proceedings (U.S. Colonials, Counterfeits and West Indies), and numerous Colonial Newsletter and Penny-Wise publications. Sold colonial collection via Stack's (2008 Americana sale) and Coin Galleries (sales in 2008-2009). Currently (2018) MNA Member and specializing in Spanish American coinage, Mexican War of Independence coinage, world contemporary counterfeits, paper money and error coins. Author of Forgotten Coins of the North American Colonies - 25th Anniversary and co-author/contributor to the Gurney/Nichols/Lorenzo (GNL) Counterfeit Portrait Eight Reales book.

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2017

Forgotten Coins Of The North American Colonies 2017 (25th Anniversary Edition)

A series of in-depth studies on counterfeits and forgeries of colonial-era coins, including Blacksmith Tokens, Two Reales, contemporary counterfeits, modern forgeries, and contemporary counterfeit English & Irish halfpence and farthings.

Note: This is an in-copyright publication, full view is not available on NNP. "Snippet" extracts will appear in NNP search results. The work is available via Amazon (as of 2/2018) at https://www.amazon.com/Forgotten-Coins-North-American-Colonies/dp/1981898042.

3/6/2020

The 1821 Zacatecas Eight Reale Non-Homogenous Surface Puzzle ? Cleaned or the Result of an Improper Mercury Amalgamation Manufacturing Process?

Lorenzo argues that surface issues on 1821 Zacatecas eight reale coins are caused by imperfect manufacturing and should not be considered the result of cleaning. Coin were examined via stereo microscope in addition to SEM/EDS testing.

6/5/2025

Clyde Hubbard’s Upside-Down Monclova Mint Stamp on a GNL Eight Reale Class 1 (Pre-1830) Contemporary Circulating Counterfeit

This is a detailed numismatic study analyzing a unique Mexican 8 Reales coin from the early 19th century bearing an unusual upside-down 1812 Monclova mint stamp. The coin, once in the collection of Clyde Hubbard, was flagged as potentially counterfeit due to atypical characteristics such as differing cartouche sizes for "MVA" and "1812" and the absence of a stop after "MVA." The host coin itself was identified as a known pre-1830 counterfeit variety (GNL#1811-O: Mo HJ-001).

The author compares it to known genuine Monclova mint issues and uses advanced SEM/EDS (Scanning Electron Microscopy/Energy Dispersive Spectroscopy) analysis to determine whether the coin is cast or die struck. The broader study aims to evaluate whether this coin was a genuine mint product or a contemporary or later counterfeit, using both visual diagnostics and metallurgical properties.

The paper establishes a comparative analytical framework by examining five coins—both genuine and counterfeit—via a three-tier SEM/EDS method: elemental composition, microstructure imaging, and pinpoint compositional mapping. The genuine Monclova specimens all exhibit consistent cast dendritic microstructures and near-regal silver content (~90% Ag), while the Hubbard specimen, although struck and not cast, also showed high silver content and diagnostic features associated with contemporary counterfeits. Despite its anomaly, the coin lacks the clear hallmarks of a forgery, and its purpose—possibly as a test piece—remains unresolved. The study concludes by affirming the efficacy of SEM/EDS in numismatic authentication and calls for further investigation of outlier specimens like the Hubbard piece.

9/15/2025

Is it Regal or Non-Regal? Unraveling Regal Looking Off-Metal Two Reales Utilizing a SEM/EDS Triple Tier Analytical Approach

This paper discusses the analysis and classification of contemporary circulating counterfeit (CCC) Two Reales coins, focusing on their composition and manufacturing methods to determine their authenticity and characteristics.

The study focuses on Kleeberg CCC (contemporary circulating counterfeits) Two Reales, with a review of probable off-metal alloys. Initial XRF surface analysis indicated discrepancies in the classification of these coins. Various manufacturing methods, including casting and die transfer processes, are discussed. The paper emphasizes the need for SEM/EDS analysis to differentiate between casting and striking methods.

3/19/2026

Surface and Grading Issues in Honduran Provisional Eight Reales at the Tegucigalpa Mint: Insights from a Dual Analysis Method: XRF and SEM/EDS Analysis

[Abstract] The provisional Honduras 8 Reales examined in this study exhibit a heterogeneous Cu–Pb alloy microstructure characteristic of mid‑19th‑century Central American emergency minting. Bulk XRF analyses across the group show Pb contents ranging from low single‑digit percentages to values exceeding 20%, while SEM/EDS spot analyses consistently return much lower Pb readings due to their shallow penetration depth and narrow sampling footprint. This divergence reflects the alloy’s intrinsic segregation behavior: lead exists not as a uniformly dissolved solute but as discrete, mechanically entrained micro‑domains that are only partially captured by localized SEM interrogation.

Microstructural imaging reveals a wrought, struck fabric dominated by elongated copper-rich matrices intersected by deformation bands and twin lines produced during striking. Within this matrix, Pb-rich globules and streaks appear as bright, discontinuous inclusions, often aligned with strike‑flow direction. These features confirm mechanical working rather than casting, as no dendritic networks, interdendritic porosity, or shrinkage structures are present. The dark Cu-rich fields and bright Pb-rich islands form a diagnostic pattern consistent with low‑technology alloying and insufficient homogenization during the provisional minting period.

Surface morphology further reflects the metallurgical instability of Cu–Pb alloys at these compositions. Lead’s immiscibility in copper promotes microcratering, localized pull‑out, and shallow pitting where Pb-rich particles intersect the surface and detach under wear or corrosion. These effects explain the irregular, granular surfaces often misinterpreted as corrosion or counterfeit indicators; instead, they are predictable consequences of Pb segregation in a mechanically struck Cu matrix. No evidence of casting defects or counterfeit microstructure was observed in any specimen.

Together, the combined SEM/EDS and XRF dataset establishes a coherent metallurgical profile for authentic Honduras Cu/Pb 8 Reales: a wrought copper matrix containing variably segregated lead domains, producing heterogeneous analytical readings and distinctive microstructural textures. These findings provide a reliable framework for distinguishing regal Honduras issues from modern fabrications and for interpreting the alloying practices, manufacturing constraints, and diagnostic surface features of this historically important emergency coinage.