Agnello was later involved in assaying the tons of black ore brought back to England on Frobisher's second voyage to Baffin Island in 1577. Between 1 November 1577 and 6 March 1578 Christopher Schutz performed three 'great proofes' of this ore. Agnello and another German metallurgist working in England, Burchard Kranich, also assayed the ore. Kranich and Schutz were soon at odds, with Schutz accusing Kranich, who was favoured by Martin Frobisher, of 'evil manners and ignorance'. Numerous documents survive showing Kranich's involvement in the assaying of the ore, including a letter of 26 November 1577 in which Kranich reported to Sir Francis Walsingham on the amount of gold found in his tests. Amid growing doubts about the value of the ore, Kranich insisted that it contained a significant amount of gold, and asked for £200 and a daily wage of £1 to refine it. On 20 December 1577 Agnello submitted his own report to Walsingham on the amount of gold to be found in the ore. According to Castells an English alchemist named George Wolfe was then brought in to assist Agnello; there were disagreements as to methodology, after which Agnello was 'shut out of the enterprise'.Other sources do not state that Wolfe was Agnello's assistant; .
