484 



PROCEEDINGS OF THE NATIONAL MUSEUM. 



vol. 40. 



columns II to IV are given analyses of examples of tektites from 

 Tasmania, Australia, and Bohemia for purposes of comparison. It 

 may be well to note, incidentally, that H. S. Summers has discussed 

 the various published analyses of the Australian " obsidianites " from 

 the standpoint of the modern classification, and relegates them to the 

 classes almerose, riesenose, urallaose, and piemenose. 



Analyses of Tektites. 



Constituent. 



IV. 



Si0 2 



AI2O3.... 



Fe 2 3 



FeO 



MgO 



CaO 



Na^O 



K 2 



H2O+IOO 

 H 2 O-100° 



Ti0 2 



MnO 



S0 3 



75.87 

 14.35 

 0.22 



0.29 

 0.00 

 3.96 

 4.65 

 0.33 



69.80 

 15.02 

 0.40 

 4.65 

 2.47 

 3.20 

 1.29 

 2.65 



Trace. 

 '""6." 23' 



0.80 

 0.18 



76.25 

 11.30 

 0.35 

 3.88 

 1.48 

 2.60 

 1.23 

 1.82 

 0.32 

 0.02 

 0.65 

 0.06 



77.96 

 12. 20 

 0.14 

 3.36 

 1.48 

 1.94 

 0.61 

 2.70 



0.10 



Total. 



90 100. 37 99. 96 



I. Obsidian pebble. Colombia. Analyst, J. E. Whitfield. 



II. Obsidianite. Upper Weld, Tasmania. Analyst, W. F. Hillebrand. 



III. Obsidianite. Near Hamilton, Victoria. Analyst, G. Ampl. 



IV. Moldavite. Tribitsch, Bohemia. 



Although data are lacking regarding the mode of occurrence of this 

 Colombian material, it is at once evident that we are dealing with a 

 not unusual type of terrestrial obsidian. 



(2) Obsidian pebbles, Clifton, Arizona (Cat. No. 53676). — These 

 pebbles were received at the Museum in 1889 from Mr. Frank Keppler. 

 There is apparently no question but what they are water-worn and 

 corroded pebbles of ordinary obsidian. They are dark, smoky black 

 in color, and show under the microscope the characteristic black hair- 

 like trichites. The surfaces are roughened by pits and grooves, as 

 shown somewhat enlarged in pi. 62, fig. 3. In addition the entire 

 surface is shagreened. 



(3) Obsidian pebbles, near Marsh, Idaho (Cat. No. 77784). — These 

 pebbles, again, are of ordinary black obsidian, and were collected by 

 Dr. W. Lindgren, of the U. S. Geological Survey, in gravel beds some 

 4f miles north and 20 degrees west of Marsh. The surfaces, as shown 

 in pi. 62, fig. 4, are everywhere pitted and grooved, but the elongated, 

 curvilinear, and lunar crater forms so characteristic of the billitonites 

 are quite lacking. The surfaces are coated with a thin, mammilated 

 crust, which is in part a secondary deposit of iron. 



(4) Obsidian pebble, High Rock Canyon, Nevada (Cat. No. 35270). — 

 This pebble (pi. 62, fig. 5) is of a coal black obsidian, only faintly trans- 

 lucent on the thin edges. The surface, it will be noted, is etched in a 

 manner strikingly suggestive of the billitonites, even to the nearly 



