Hamblin CouiUy^ Tennessee^ Meteorite. 



151 



however, that of a clastic rock, but rather that of a crys- 

 talline variety which has been subjected to dynamic agencies. 

 The structure as a whole is quite irregular, and as above noted 

 porphyritic through the presence of large ]3yroxenes which at 

 times are 5 to 8™"" in diameter. 



The groundmass of the stone is composed mainly of gran- 

 ules of pyroxenes and plagioclase, of such size as to render 

 their determination by the microscope a matter of considera- 

 ble ease, but which are interspersed with innumerable rounded 

 and irregular granular forms so minute and so lacking in crys- 

 tal outlines as to render their true mineralogical nature a mat- 

 ter of conjecture only. 



The feldspars as a rule show polysynthetic twinning. Sections 

 without twin striae (and which are assumed to be approxi- 

 mately to oo P ^ ) show the emergence of an optic axis just 

 outside the field, and give extinction angles as high as — 38°, 

 vsuggestive of anorthite. By means of a specific gravity solu- 

 tion a small quantity of the feldspars (0*19 grm.), was separated 

 out and analyzed, with the results given below, and which 

 confirm the result of the optical determination. They usu- 

 ally contain a large number of cavities and enclosures, as 

 shown in fig. 2, in this respect, and with respect to their shat- 

 tered condition as well, resembling those of the Sierra de 

 Chaca stone. 



Feldspar out of Meteorite. 



SiO, _- 42-02 



Al,03 .__ 37-77 



FeO _ trace 



CaO 16-41 



MgO ' 0-96 



Na„0 not det 



97-16 



