Georges-Louis Leclerc comte de BUFFON. 2 manuscripts with autograph corrections, Minéraux 3 and 2 pages in-4. Two working manuscripts for the Histoire naturelle des minéraux (1783-1788). These manuscripts are in the hand of Trécourt, Buffon's secretary from 1774 to 1783. They belong to the 15th notebook of the 3rd volume of the Minerals, as indicated by a note at the head of the leaves. Crystaux Topazes (15th Book 2); numerous corrections and additions by Buffon, with 2 marginal additions by his collaborator Abbé Gabriel Bexon (1747-1784). The beginning in particular has been redone by Buffon: "One has wrongly given the name of topaz to these stones which are found in Germany, in France and in several other provinces of Europe"... Aquamarine (15th Book 4); numerous corrections and additions by Buffon, who in particular added the final sentence: "Ainsi l'on ne peut douter que cet aigue marine ne soit un crystal".