BEDIASITES - MULDOON AREA, FAYETTE COUNTY & GRIMES COUNTY, TEXAS, USA

The following information is condensed from a chapter authored by E. Chao entitled “The Petrographic and Chemical Characteristics of Tektites”, which appeared in “Tektites”, edited by John A. O’Keefe, P. 51-94 (1963). In section 3.3, Chao writes: bediasites occur in an area about 140 miles long and 5 miles wide in east-central Texas, in a belt extending from Gonzales County in the southwest to Grimes County in the northeast. The Muldoon area, in Fayette County, is in the southwest part of the strewnfield.  The rounded bediasites from this location range in diameter from less than 1/4” to 3/4” and, at a distance, are jet black in color.  Close examination, with transmitted light, shows they are actually smoky gray to light olive-brown in color. Table l on P. 7 of “Tektites”, provided by G. Baker, lists the basic shapes of Texas Bediasites as: spalls, spheres and spheroids, tabular forms, and occasionally lenses and teardrops.  They occur in a layer of lag gravel, several inches thick, of post-Eocene and pre-recent age.  The age of the bediasites determined by the K/A method is 29.0 million years.

P. M. Bagnall, in “The Meteorite and Tektite Collector’s Handbook”, P. 114 (1991) reports that “unlike meteorites, tektites are not scattered randomly across the globe but instead are located in fairly well-defined areas known as strewnfields, seven of which are generally recognized.  By far, the largest is the Australasian Strewnfield.  Texas bediasites are from the second largest recognized strewn field -- the North American Strewnfield.  At about 35.0 million years old, it is the most ancient of all the strewnfields.” 

As a comparison, the ages of the various tektite groups are given in Table 12, on P. 136, in “Tektites”, by V. and M. Barnes.  Bediasites and Georgia tektites, both from the North American Strewnfield, are reported to be between 33.7 and 35.0 million years old.  Moldavites are estimated to be between l4.4 and l4.9 million years old, Ivory Coast tektites are 1.3 million years old, and all of the Australasian tektites (Australites, Indochinites, Javanites, and Philippinites) are between 0.68 to 0.76 million years old.

The specimens available here were collected in 1947.  They are fairly rounded in physical appearance, black in color (smoky gray to light olive-brown when examined with transmitted light), with a matte luster.  Most exhibit a small amount of sculpturing and/or micro pitting.  Texas bediasites generally average between 1.0 and 5.0 grams in weight -- pricing is @ +/- $9.00 per gram for specimens in the < 5.0 gram size range. Specimens > 5.0 grams are uncommon, and are priced accordingly at +/- $10.00 / gram.  All sizes are given in inches: length X width X thickness. Order item BED-A through BED-K.