Share of 1000 francs N°851 of the Mines de Houille de Kergogne (Finistère), issued in Nantes on 16 June 1840 by the house Marc Thomas Aubert & Cie. In 1840, under the July Monarchy of Louis-Philippe, the industrial and mining fever was at its height in France. Kergogne is a place-name in the Finistère, and the idea of exploiting coal there may seem surprising: Brittany is not a known coalfield region. Yet anthracitic coal deposits exist in certain parts of the Armorican Massif, and several exploitation attempts were made in the 19th century. The fact that this certificate was issued from Nantes (a major commercial and port city) by the house Aubert & Cie testifies to an ambitious capitalist initiative. This document, at over 185 years old, is an exceptional collector's piece for its age, rare Breton theme and state of preservation.