1922] A Magnetite-Marble Ore at Lansing, N. C. 141 



made up mainly of equi-dimensional prisms of actinolite that are 

 pleochroie in very light yellowish green and emerald-green tints. 

 These alternate with equally thin layers of carbonates. The maximum 

 extinction of the actinolite is about 20°. Among the actinolite prisms 

 are scattered a few large grains of carbonate, a very few large plates 

 of a colorless mica, perhaps phlogopite, and large irregular masses of 

 magnetite. The actinolite appears as though in crush zones, and its 

 individual prisms have a general parallel elongation in the direction 

 of the layers. In many cases the magnetite masses are crossed by tiny 

 cracks filled with calcite. It is noticeable that the major portion of 

 the magnetite within the layer characterized by the actinolite is usu- 

 ally associated with the carbonates that are always present in it. 

 In some places, however, the magnetite and actinolite are so free from 

 carbonates that the rock is locally a magnetite-actinolite schist. 



Around the lenses of magnetite in the marble are often envelopes 

 of actinolite and often there are veins of actinolite cutting through 

 them. In these cases the magnetite is cleaved so that the lenses appear 

 to be granular masses composed of elongate grains of the magnetite. 

 The long dimensions of the magnetite and the long directions of the 

 actinolite fibers in the veins are parallel, but there is no definite re- 

 lation between the elongation of the fibers and the directions of the 

 veins. The fibrcsity may be parallel to the walls of the veins, per- 

 pendicular thereto, or inclined to them at any angle. Whatever their 

 direction with respect to the veins, they are all parallel within the 

 mass of a single hand-specimen. 



In other specimens veins of actinolite traverse masses of magnetite 

 and marble, and sporadic garnets appear in the mass. 



The suggestion furnished by the sections is that a mass of marble 

 and magnetite, with some actinolite, became shattered as the result 

 of movements, and the cracks between the fragments of magnetite were 

 filled with actinolite formed from magnetite and some of the constit- 

 uents of the marble by metamorphosing processes during the course 

 of this movement. In some cases calcite which was undergoing recrys- 

 tallization at the time was also forced into the fractures. 



There was evidently motion in the rock-mass also after the actino- 

 lite was formed and after the magnetite was shattered, since there 

 are present in the rock sliekensides coated with acicular actinolite, in 

 many cases to a thickness of one-half an inch or more. Inthese cases there 



