Contributions of Andres Manuel del Rio

Although A. M. del Rio, the eminent discoverer of the element now known as vanadium, spent most of his active life in Mexico and a few years in Philadelphia, his services to chemistry and mineralogy are not as widely known and appreciated by American scientists as they deserve to be. He was a schoolmate and honored friend of Baron Alexander von Humboldt and a worthy colleague of Don Fausto de Elhuyar, first director of the School of Mines of Mexico. 

In 1793 a royal order decreed that Werner s theory of the formation of veins be taught at the School of Mines of Mexico recently founded by Don Fausto de Elhuyar (2). The professorship of mineralogy was therefore offered to Senor del Rio, who had previously declined that of chemistry. Early in August, 1794, he set sail from Cadiz on the warship San Pedro Alcantara, taking with him a servant and a supply of apparatus for the School of Mines. Eleven weeks later he disembarked at Vera Cruz (3). 

In 1795 he published the first edition of his Elements of Oryctognosy (5), which von Humboldt regarded as the best mineralogical work which Spanish literature possesses (6), and which Santiago Ramirez (7) called a monumental work, which. . . will be an object of veneration and consultation by the mineralogists of our country and for all those who. . . are occupied in studying the mineralogy of our native country.  

Del Rio s paper on the best method of sinking mine shafts was printed for use in all the mines of Mexico, and his article on the relations between the composition of a mineral and the materials of which the vein is composed was published in the supplement to the Gaceta de Mexico on January 18, 1797 (1,3). 

The most outstanding achievement of del Rio s long, useful life was his discovery in 1801 of the metal now known as vanadium. He found that the brown lead mineral, Plomo pardo de Zimapan (8), from the 

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