After working with his brother for a number of years, José set off to find new mineral strikes, arriving to
Tlalpujahua in 1734. Here he founded a mine that was very successful. In 1738, his brother Francisco died and Borda inherited his brother's property. Deeper exploration of the original La Lajuela mine yielded an abundance of silver. It is from this strike that Borda first funded the building of the Santa Prisca Church. When this mine had nearly run out, he discovered a richer one in the Taxco called San Ignacio. With this money, he rebuilt and expanded the Santa Prisca Church. However, the San Ignacio mine produced for only nine years. By 1760, Borda's mines had run out, forcing him to explore in
Real de Monte and then in Chontalpan in 1761. By this time, he was practically bankrupt. Borda mortgaged the last major possession he owned in Taxco, the richly ornate Santa Prisca Church, in order to finance an expedition to Zacatecas. Once there, he initially worked in a mine called “La Quebradilla” but it did not produce as much as hoped and payments were coming due on the mortgage. With the last of his money, he opened the mine “La Esperanza” which again made him a wealthy man. With this new mine, Borda became the richest man in Zacatecas, as he had been before in Taxco. He was named a regent of Zacatecas. By 1776, the aging Borda was affected by
mercury poisoning and other illnesses. He wanted to return to Taxco, but his son Manuel convinced him to retire to the family house in Cuernavaca, where he thought the climate would be better. Here, Manuel was already living and practicing as a priest. Just before Borda died in 1778, his son administered
last rites. In total, Borda's earnings from his mines in Mexico totaled 40 million pesos, and at the heights of his career was the richest man in Mexico and perhaps the world. ==Architectural works==