Domestic regd. cover to Bétroka with mining cachet EXPLOITATIONS DE MINES ABEL LOUYS AGENCE DE BETROKA (receiving mark on reverse). Exploitation started here in 1924. Large pockets with large phlogopite crystals has been found in the JS.9 mine, the largest measured 4 m in length and 2 m in diameter and weighed 27,5 tons ! The JS.9 mine was mined from 1948 to 1953.
Prüfung: original
