UK, 1824: Platina ore adulterated

January-December, 1823: 1 Troy Oz. Platinum (refined) = £ 1.28 - £ 1.5039

In 1824, Dr. Wollaston recorded Rhodium receipts of £ 42.75
 
In an 1824 treatise, Accum's old partner Fredrick Joyce warned consumers of duff platina sold by vendors.  Best quality ore samples were 55% - 65% Platinum, c. 1823/4.


c.1824 
Citation Practical chemical mineralogy; or, Concise and easy methods ... for readily; Frederick Joyce, 1825

In mid-1824 (?) a single cell of Wollaston's Voltaic battery cost £0.17 ; in 1825, a larger platino-zinc pile in Germany cost >5 x more.  Assuming a common thickness and 120 sq. in. per English Troy Ounce, ~£1.10 for 160 sq. in. Pt (for the English set, in 1824) and ~£0.50 for 24 sq. in. Pt (for the single German unit, in 1825) makes German Platinum ~3.25x more expensive by weight, less than a year later.

Citation: The Chemist (November 1824) p. 158

c.1824 Suggestion of Gold Foil-covered Platinum counterfeit Sovereigns.  The surface area of a full-weight, milled-edge Sovereign should be ~9.42 cm² (1.46 Sq. In.) Whereas a full-weight Sovereign ought to weigh 7.988 g. (.91665 Fine), a well-gilded counterfeit might have as much as 2.2 g. Gold alloy (~2 g. Fine Gold) with a Platinum alloy core weighing 5.8 g. 

For the correct Specific Gravity (w/ Sb & Cu), which most counterfeiters failed to achieved, the Platinum alloy should have been between 87%-91% Pt (~5.10-5.30 g.)

Dr. Wollaston claimed his refined Platinum had a Specific Gravity between 21.25-21.5, but contemporaries preferred and noted the better quality or French crucibles. 

Even assuming the an English counterfeiter already had the necessary tools (otherwise, a capital outlay), the purchase of refined Platinum was certainly not economical; commercial Platinum for the flan or planchet would have cost £ 0.25, before any cost for additional materials, labor and above any routine costs for such a criminal endeavor. 

Given the extant technology prior to the 1830s (when cheap plating with Galvanic batteries was known), this particular type of false coining would not have been remunerative or profitable, unless the counterfeiter had been a chemist or refiner (such as a Mint employee) and with access to cheap ore.