PETROLOGICAL ABSTRACTS AND REVIEWS 641 



Richards, H. C. "The Building Stones of Queensland," Proc. 

 Roy. Soc. Queensland, XXX (1918), 97-157, pis. 3, figs. 10. 

 The physical, chemical, and mineralogical characters of various available 

 building stones, with their good and bad qualities, and a list of structures with 

 the stones used, are given. 



Richards, H. C. "The Volcanic Rocks of Springsure, Central 

 Queensland," Proc. Roc. Soc. Queensland, XXX (1918), 179- 

 98, pi. I, figs. 6. 

 The oldest rocks of this area are Paleozoic sediments, consisting of sand- 

 stones, gravels, and shales, and some limestone. The volcanic rocks, with a 

 total thickness of 1,000 feet, are divided into three groups: a Lower Series 

 which consists of basaltic agglomerate and basaltic flows, followed by trachyte 

 tuffs and flows, then a return to basaltic flows. The Middle Volcanic Series 

 consists of trachytic tuffs and flows which are "really phonolite in the strict 

 petrological sense." In the weathered material, precious opal has been 

 obtained. The Upper Volcanic Series consists of basaltic flows to a thickness 

 of 600 feet. Three new chemical analyses are given. The upper and lower 

 basalts are similar and closely comparable with the composition of the average 

 basalt of the world. Richards says: "The basaltic rocks. . . . may represent 



outpourings of a comparatively undifferentiated primary basaltic magma 



Gravitative differentiation may have gone on to some extent as the lower series 

 is olivine free, while the upper series is rich in olivine (fayalite). . . . The 

 intruded terrane almost certainly contains limestone, and the solution of this 

 material to a small extent would be regarded by Daly as sufficient to result in 



the production of the phonolitic material from the calcic basic magma 



The writer, however, in dealing with the origin of the volcanic rocks of south- 

 eastern Queensland, regarded them as being differentiates of a single original 

 magma." 



Richardson, W. Alfred. "The Marginal Features of a Basic 

 Dyke at Peldar Tor, Charnwood Forest," Geol. Mag., LVIII 

 (1921), 170-77. 

 A much altered greenstone (dolerite) dike which intrudes dacite shows a 

 chilled marginal phase and a crystalline center. At the contact the margins 

 are laminated, resembling columnar basalt, but actually consist of alternating 

 sheets of country rock and dike. Three possible explanations for the lamina- 

 tion are given. 



Richardson, W. Alfred. "A Method of Constructing Rock- 

 Analysis Diagrams on a Statistical Basis," Miner alog. Mag., 

 XIX (192 1), 130-36. 

 Diagrams for plotting the chemical analysis of a rock are given. 



