 The richest vein of silver was the Veta Vizcaina, or the Vizcaina Vein, which extended 5 km to the east of Real del Monte.Productive mines along this vein included the San Francisco, Santa Agueda (1767), Santa Teresa (1734), La Joya (1734), San Cayetano (1751), Dolores (1734), and La Palma (1734).By 1750, Pedro Terreros had control of this lucrative vein.