The Valverdites: A Weathered Obsidian Form Superficially Resembling Certain Tektites*

Abstract

This paper is devoted to a critical study of the natural glasses recently found in Val Verde County, Texas. On the basis of the behavior of these so‐called valverdites under the blowpipe flame; of their low densities and indices of refraction; of the crystallites and megascopic crystals contained in them; and of their other peculiarities, the conclusion is reached that they are not tektites, but are weathered pebbles of obsidian.

Distribution and sources of obsidian in the Rio Grande gravels of New Mexico

“…Further south, subsurface trace amounts of obsidian are reported from well borings in the Mesilla Valley (Mack, 1985). Obsidian and cherts continue to be present in Rio Grande gravel deposits further south (Paz, 1948;Dake, 1952). Belcher (1975) investigated gravel deposits along the entire course of the Rio Grande, and the deposits were used to plot hypothetical channel development.…”

“…Paz, 1948 Figure 2. Distribution of ancestral and historic Rio Grande gravels in the study area (from .…”

Obsidian and mafic volcanic glasses from the Philippines and Vietnam found in the Paris Museum Australasian tektite collection

“…They may be widely dispersed and be misleadingly proposed as new tektite occurrences, thus the term "pseudotektite" (see recent discussion of such an occurrence, named the Cali glass strewn field in Colombia by Ferri ere et al, 2021). Other such "pseudotektite strewn fields" are known in many volcanic areas around the world although not always published as such (but see examples from the Philippines and Patagonia in Koomans [1938]; macusanite from Peru by Martin & De Sitter-Koomans [1956] and Craig et al [2010]; from Central America in Mrazova & Gadas [2011]; from western USA in La Paz [1948] or Rochette et al [2015]). The dispersion of volcanic glass pebbles or fragments away from their source volcanic formation may be due to erosion (with river transport over tens of kilometers) or human transport.…”