Appendix B - Nodule Examples

A brief description and photographs of material from a few obsidian sources in the region. The map and table in Section 4.2 - "Tectonic Geology" and discussion in Section 4.4 - "How obsidian is formed" provide additional information relevant to this list.

B.1. Aconcagua

Other names: Aconcahua
Latitude: -16.8422
Longitude: -69.8632
Reference: Frye, Aldenderfer, Glascock 1998.
West of Mazo Cruz (Puno) and east of Osmore (Moquegua), Peru

Figure B-1. Nodule from the Aconcagua source. Photo courtesy of Mark Aldenderfer.

B.2. Alca

Other names: Umasca, Cusco Type
Longitude: -72.6928
Burger, Asaro, Trawick and Stross 1998b; Jennings and Glascock 2002; Rademaker, Sandweiss, Malpass, Umire, de la Vera Cruz, Fortin and Morris 2004.

Southeast of Alca in the Cotahuasi Valley, Arequipa, Peru. A University of Maine team has recently located primary deposits on the north flanks of Nevado Firura at 4400 to 4800 masl, a higher elevation zone than was indicated by previous studies.

Figure B-2. Some nodules of Alca obsidian have a brownish tint.

B.3. Chivay

Other names: Cotallalli, Cotallaulli, Titicaca Basin Type
Latitude: -15.6423
Longitude: -71.5355
References: Brooks et al. 1997; Burger et al. 1998a.

East of Chivay in the Colca Valley, Arequipa, Peru. Photos below show examples of Chivay obsidian nodules.

Figure B-3. Nodule of Chivay obsidian from Maymeja weighing 1750g and 23.3 cm long. This nodule was not utilized (scars are geological in origin), perhaps because it has irregularities in the form of tiny crystals.

The nodules below were selected to show the variability of cortex encountered in the source area.


(c) (d)

Figure B-4. Chivay obsidian (a, L03-161.341) nodule from quarry pit area with thin, angular cortex with tephra welded to exterior; (b, L03-160.178), an unmodified side of a grey core showing rough, tabular cortex with rounded corners, reddish tint is just a reflection. Three large flakes (not showing) were removed from opposite side of this core (c, L03-165.37) Core with cortical face of extremely thin cortex, some of the cortex is glassy while other parts appear opaque and perlitic; (d,L03-159.194) a core with cortical face on right showing a thin but "corduroy" cortex, and small quantities of light tephra welded to the outside.

B.4 Uyu Uyu

Other names: Oyo Oyo, Caracachi
Latitude: -15.6155
Longitude: -71.6760
Brooks 1998, Wernke 2003.

North of town of Ichupampa in the main Colca Valley.

Figure B-5. Nodule of Uyo Uyo obsidian with irregularities perhaps caused by air bubbles in the magma.