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Named stone

Cerro Toledo obsidian

Also called Obsidian Ridge obsidian, Cerro Toledo Rhyolite obsidian, Rabbit Mountain obsidian

A kind of obsidian

Cerro Toledo obsidianObsidianTexas & Southwest

Description

Cerro Toledo obsidian, long called Obsidian Ridge obsidian, comes from the Cerro Toledo Rhyolite eruptions on the edge of the Valles Caldera in the Jemez Mountains. The loose volcanic ash there is full of obsidian, in nodules from pea-size to over 16 cm, and even bigger near Rabbit Mountain. One locality had up to 200 nodules per square meter, among the densest obsidian deposits in the Southwest. Quality varies a lot: some pieces are excellent translucent brown aphyric glass, while others have large devitrified spherulites that make knapping impossible, so people test-knapped heavily at the source. Erosion carries the glass into the Rio Grande, and it is the main Jemez glass at Jornada Mogollon sites and in the Clovis assemblage at Mockingbird Gap.

How to identify it

Colour
Excellent aphyric translucent brown glass in the best pieces (Shackley).
Texture
Varies from clean glass to glass with large devitrified spherulites that stop knapping.
Inclusions
Devitrified spherulites in poor pieces.

Geology

Cerro Toledo Rhyolite: six pyroclastic eruptive events with Plinian pumice falls and ash. Obsidian lies in the Rabbit Mountain ash flow and base-surge deposits and in a 20 km-wide ash flow band that erodes into the Rio Grande alluvium north of Santa Fe. Obsidian from this unit is an integral part of the Rio Grande alluvium north of Santa Fe.

Where it comes from

Texas & Southwest

States

Quarries and outcrops

  • Obsidian Ridge, southern edge of the Valles Caldera, Jemez Mountains
  • Rabbit Mountain and the ridges west toward Cochiti Canyon
  • Rio Grande alluvium north of Santa Fe

Used by

  • Clovis: six Cerro Toledo artifacts from the Mockingbird Gap surface collection and two from Socorro and Catron counties (Hamilton and others 2009)
  • Used throughout time in the Jornada Mogollon region (Dolan and others)
  • Cody complex: seven Cody artifacts sourced here (LeTourneau and Shackley, as cited by Dolan and others)

Look-alikes

Stones that are easy to confuse with Cerro Toledo obsidian.

Sources

  1. Shackley, M. Steven. Geoarchaeological XRF Laboratory, University of California, Berkeley. Southwestern obsidian source description: Jemez Mountains and the Sierra de los Valles.swxrflab.net (opens in a new tab)
  2. Hamilton, Marcus J., Bruce B. Huckell, and M. Steven Shackley. 2009. Clovis Obsidian Sources in the Central Rio Grande Rift Region of New Mexico. Current Research in the Pleistocene 26:62-65.unm.edu (opens in a new tab)
  3. Dolan, Sean G., Judy Berryman, and M. Steven Shackley. 2016. The Source Provenance of an Obsidian Eden Point from Sierra County, New Mexico. PaleoAmerica (accepted manuscript, Los Alamos National Laboratory LA-UR-15-28702). https://doi.org/10.1080/20555563.2016.1138822osti.gov (opens in a new tab)

Points made from this stone

All materials