438 T. T. QUIRKE 



centration. Parts of the veins have "been examined in both 

 poHshed surfaces and in thin sections under the microscope. The 

 metal seems to have been deposited without any violence having 

 affected the chondrules, as a general thing; however, one chon- 

 drule seems to be represented by only half a sphere, the metal being 

 in juxtaposition with the plane side. In most cases, nevertheless, 

 the metal or sulphide partly surrounds or incloses the unbroken 

 chondrules. The writer has seen no case of a chondrule penetrated 

 by metal, although some of the chondrules include tiny grains 

 of troilite in bordering zones. In cases where both metal and sul- 

 phide are in the vein the two are mingled in irregular shapes 

 which have a smooth surface of contact; in some cases the troilite 

 is scattered both within and near the borders and outside the 

 metal, in other cases taking the place of the chief constituent of 

 the vein and containing small irregular grains of metal. 



Iron and troilite veins are not uncommon in stony meteorites. 

 In some cases both minerals are present, and in others there is 

 but one. Of American falls the following are reported definitely 

 to contain iron veins: Danville,^ Marion,^ Farmington,^ Estacado,'' 

 and Pipe Creek.^ Troilite veins are reported in both McKinney^ 

 and Cosby Creek.'^ In most of these the iron and sulphide are 

 concentrated apparently in the veins, although in most other 

 meteorites the iron and troilite are disseminated in irregular grains 

 throughout the mass. The relations of the minerals are com- 

 monly obscure; for example, Bath Furnace^ has troilite intruding 

 riven metallic particles as though of younger age than the iron, 

 and also troilite completely enclosed in iron, indicating the oppo- 

 site. But in Allegan^ the sulphide does not occur as blebs within 

 the iron as the silicates do, indicating that it is not necessarily 

 either antecedent or contemporaneous with the iron. In the case 



' Farrington, op. cit., quoting Smith, p. 156. 



^ Ibid., quoting Brezina, p. 296. 



3 Ibid., quoting Meunier and Preston, p. 187. 



'^ Ibid., quoting Howard and Davison, p. 174. 



5 Ibid., quoting Brezina, p. 353. 



^ Ibid., quoting Brezina, p. 291. * Ibid., quoting Merrill, p. 50. 



7 Ibid., quoting Shepard, p. 138. ' Ibid., p. 30. 



