NO. 1878 CRYSTALIvOGRAPHIC NOTES ON CALCITE — POGUE 467 



imperfectly developed at the lower end of the crystal, appears here by 

 a mere rounding. The crystal is twinned parallel to the basal plane 

 c (0001), following a common law for calcite. The feature of inter- 

 est is a moving bubble, which has a free course over the area outlined 

 by dots in the drawing. This space is roughly rectilinear in shape, 

 about 16x6.5 mm. in size, and is situated i to 3 mm. beneath and 

 parallel to the surface; its edge of greatest length is also approxi- 

 mately parallel to edge -in/_ of the crystal. The space is apparently 

 located in a definite manner in regard to the orientation of the calcite. 

 Complex twins from the same locality have been described by 

 Pirsson.^ 



(3) Calcite from Virgieina, Virginia 



A small suite of calcite crystals have been found in the-Virgilina 

 copper district of Virginia by Dr. F. B. Laney, who kindly placed 

 the material at the disposal of the writer. As no descriptions of 

 calcite from this locality, so far as the writer knows, appear in the 

 literature, a brief note is deemed desirable. 



Crystallized calcite occurs at the High Hill Copper Mine, Halifax 

 County, Virginia, about nine miles north of Virgilina. It is found 

 in small cavities or vuggs, distributed at irregular intervals in a 

 quartz vein 4 to 8 feet in width, which traverses a greenstone schist 

 (probably a mashed andesitic tuff). The crystals are rare and are 

 associated with crystalline quartz, cuprite, malachite, and one or more 

 other copper minerals. The mine is 300 feet deep, but the depth 

 from which the present specimens were obtained is not known. 

 Massive calcite as a gangue is not common at this mine, though very 

 prominent at the Blue Wing Mine in the same district.- The crystals 

 range in size from i to 7 mm. in greatest length and occur in two 

 distinct types. 



Type I, shown enlarged in plate liv, figure 2, is rarer and smaller 

 than type 2 (figs. 3 and 4). The former is very simple, being a com- 

 bination of the positive rhombohedron r (loii) and the rare scalcno- 

 hedron G: (72^^)} This form was noted by Farrington and Tillot- 

 son* on calcite from Joplin, and by Palache^ on calcite from the cop- 

 per mines of Lake Superior, but has not otherwise been described on 



' Amer. Journ. Sci., vol. 41 (1891), pp. 61-64. 



■ For these details of occurrence the writer is indebted to Dr. Laney. 

 ^ Goldschmidt's symbol. This form is not given in Dana's Mineralogy. 

 *Publ. Field Columb. Mus., Geol. Ser., vol. 3 (1908), p. 141. 

 "Zeitschr. fiir Krj'st., vol. 24 (1S95), p. 589; Mich. Geol. Survey, vol. 6, pt. 

 2 (1898), p. 168. 



