Orbicular Gabbro. — Kessler and Hamilton. ii^i) 
cally the same in both. This similarity in chemical composi- 
tion seems to denote that the cause which set about the form- 
ation of the sjjheroids was not a chemical phenomenon. 
Other Occurrences. 
Orbicular granites have been noted in many localities, no- 
tably from Slatmossa, Sweden.* Also from Fonni, Sardinia.! 
An orbicular granite was descril3ed from Quonochontogue 
Beach, Rhode Island, by J. F. Kemp. J 
This quite closely resembles an appearance, the second va- 
riety of spheroid from Dehesa. Another occurrence is de- 
scribed by Hatch, from Mulaghderg, Ireland. § This resem- 
bles the orbicular dioryte of Corsica much more closely than 
does the gabbro of San Diego, the radial structure being very 
pronounced. Spheroids in the granites of Sweden were de- 
scribed by Brogger and Backstrom. || 
A nodular granite from Ontario, has been described by 
F. D. Adams. ^ This differs from other orbicular granites 
in that there is no pronounced radial or concentric structure. 
The same is true of the "pudding"' or "prune" granite of Ver- 
mont. ° 
Orbicular dioryte is represented best in the type locality, 
Corsica. It was described by Vogelsang.** AnotJier example 
was reported from Rattlesnake Bar, Eldorado Co.. Cal.. by 
Vom Rath.*** A specimen from this locality may be seen in 
the California State ^Mining Bureau ^Museum in San Francis- 
co, Cal. 
Orbicular gabbros have been reoorted from Romsas, Nor- 
way by Chrustschoff.°°and from Willow creek, Cal., by H. W. 
Turner.it This is described as an "orbicular rock which con- 
tains olivine and iron ore with much rhombic pyroxenes and 
• Sitznngsber. d. neiderrhein. Ges., Dec, 1874., p. 206. Also Kept. Smith- 
sonian Inst., 1900, pp. ~^0, pi. 6. 
t "Sur les nodules de la Oranitite de Ghestonai prcs Fonni (Sardaique)" 
Bull, de la Soc. Min.. France, tome X (1887), pp. 57-63. 
t Trans. N. Y. Acad. Sci., vol. xii, pp. 140-144-, PI. XI, 1894-, 
§ Quar.Jour. Geol. Soc, vol. xliv, p. 548. 
II Geo!. Forem. Stockl. Forhandl., No. 110, Bd. ix, Haft. 5, p. 307. 
H Bull. Geol. Soc. America, vol. ix, 1898. p. 163. 
° Geol, of Vermont, vol. ii, p. 564, 1861. 
** Sitzungsber. d. neiderrliein. Ges., 1862, vol. six, p. 185. 
*•* Sitzungsber. </. neiderrliein. Ges. zu Bonn, 1884, p. 206. 
'^^ Euber holocyrstalline macrovariolitische Gesteine, von Dr. K. von 
Chrustschoff, St. Peterslnirg. 
tt l-*t/i .inn. Rept. r. S. Geol. Surv., p. 4,74,. Also 17th Ana. Rept. U.S 
Geol. Surv.. p. 642. PI. XXX. 
