Dec 1, 2017
Postage stamps celebrating the 1st portuguese-hispanic-american congress of economic geology* issued in Portugal on September 24, 1974 by the Casa da Moeda - Portuguese Mint (later in 1972 merged with the National Printing House becoming NPH and Mint).
From left (top) to right: Beryl, Arsenopyrite, Chalcopyrite & Zinc Blend, Wolframite;
*Took place in Madrid (Spain) from the 19th to the 23rd of September and in Lisbon (Portugal) during the 24th and 25th of September;
#postage stamp#selo de portugal#selo#timbre postal#timbre#filatelia#1971#1972#mint#portuguese mint#casa da moeda#geologia#geology#portugal#volframite#clacomite#calcomite blenda#arsenopirite#geologia economica#economic geology#congress#espanha#españa#spain#berilo#beryl#arsenopyrite#chalcopyrite#wolframite#ctt
