M. Galvao da Silva, Portuguese government official, explorer and plant collector, left Brazil for Portugal around 1772 to study at the University of Coimbra. He graduated in philosophy in 1776, but also studied mining. For the next five years he worked at the museum and botanical garden [presumably in Coimbra]. In about 1783 he was appointed secretary to the government of Mozambique. On his way there he spent some time in Brazil, where he visited his parents in Bahia, investigated copper mining, studied the indigenous flora, and collected some fish to send to Lisbon. He next spent about two months in Goa, on the west coast of India, where he collected plants, animals and minerals, and subsequently published an account of his activities there.
Da Silva eventually arrived in Mozambique late in 1784 to take up his secretarial duties. His scientific activities were curtailed by his official duties, disease and other adverse circumstances, but during his ten years in government service he made some incursions into the territory and collected information on especially its mineral resources. In 1788 he was ordered by the governor-general of Mozambique to proceed to and investigate the Manica gold fields (north-east of Beira and near the Zimbabwean border at Mutare). During this journey in August to September 1788 he made an important collection of plants which he sent to Portugal, but it was broken up during the Napoleonic Wars and only scattered remnants survived. In a publication issued in Lisbon he briefly described the methods used by the native inhabitants to extract gold. Much later James MacQueen described his travels in "Journey of Galvao da Silva to Manica Gold Field, etc., in 1788, with description of the country south of the lower Zambeze" (Journal of the Royal Geographical Society of London, 1860).
After leaving government service Da Silva remained in East Africa as a merchant and probably as a slave trader.