Ortiz porphyry belt

The Ortiz porphyry belt is a cluster of small mountain ranges in Santa Fe County, New Mexico.

A second set of intrusions at 27.9 to 31.4 Ma took place after compression had reversed and the crust in the area was put into tension, and these took the form of dikes and stocks that are responsible for most of the deposits of metal ores in the mining district.

[1] The rock of the intrusions is fairly uniform over the entire belt and has been described as porphyritic andesite or monzonite.

It typically consists of a roughly equal mixture of plagioclase and alkali feldspar with smaller quantities of quartz and considerable hornblende.

This is a small-volume extrusive unit exposed around the village of La Cienega that may represent the earliest stages of opening of the Rio Grande rift.

[2] Turquoise and precious and base metals have been mined from the Ortiz porphyry belt from prehistoric times.

Spanish mining began in the 1580s with emphasis on silver and lead ores, centered on Mina del Tiro and Bathsheba.