EJIDO SIQUIRICHI

Southwestern Chihuahua, Mexico

Discovered in 2002 by John Roney, Art MacWilliams, and Robert Hard.  This marekanite source is located about 10 km west of Norogachi and a kilometer west-southwest of the community of Ejido Siquirichi in the Sierra Madre Occidental of southwestern Chihuahua (UTM Zone 13, 278989E/3017363N).

Text submitted by John Roney:

"The nodules were collected from a 20 meter diameter area in a ridge top.  The were essentially resting on rhyolitic tuff bedrock, and we believe that they are weathering out of the bedrock at this location [similar to Cow Canyon].  The largest nodule we collected here is 4.34X4.0XX2.8 cm and weighs 59 grams.  However, we only spent a few minutes at this location and with additional time we might have found larger nodules.  Furthermore, the local people who were with us indicated that grapefruit-sized nodules can be found on another ridge about a kilometer to the southwest of this location." (emphasis mine).

Even though the obsidian in nearly opaque even in the thinnest flakes, like many in the Sierra Madre, it is not a peralkaline rhyolite.  The knapping quality seems fine.  Using bipolar on the marekanites was very predictable, and relatively thin flakes could be removed easily.  So far (Fall 2014) this source has not been located in archaeological contexts.

 

Table 1.  Raw elemental concentrations for Ejido Siquirichi

Sample Ti Mn Fe Zn Rb Sr Y Zr Nb Ba Pb Th
1 1355 332 14301 75 193 56 45 274 21 1255 37 18
2 1374 349 13928 65 185 59 45 260 15 1146 35 22
3 1251 312 13005 65 178 55 45 250 15 1230 37 18
4 1310 321 13121 64 176 54 46 248 17 1080 35 19
5 1220 290 12180 59 170 48 44 246 23 1175 34 14
6 1314 331 13775 69 187 54 43 255 18 1095 35 14

 

Table 2.  Mean and central tendency for the data in Table 1.

This page maintained by Steve Shackley (shackley@berkeley.edu).
Copyright 2014 M. Steven Shackley. All rights reserved.
Revised: 19 August 2015

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