6 PROCEEDINGS OF THE NATIONAL MUSEUM vol. 124 



as metal and sulfide in the groundmass; Co is probably entirely in 

 the metal phase and is therefore almost completely absent from the 

 chondrules. 



The Bur-Gheluai Meteorite 



After detonations and the appearance of a fireball in the sky, many 

 stones fell near Bur-Gheluai in the district of Bur-Hacaba, Somalia, 

 at 8 a.m. on Oct. 16, 1919. This must have been a very large shower; 

 over 120 stones were recovered. The largest weighed 15.4 kg, 5 others 

 weighed between 4 and 8 kg, 8 between 2 and 3 kg, 21 between 1 and 

 2 kg, 16 between 0.5 and 1 kg, 52 between 0.1 and 0.5 kg, and 18 

 between 0.01 and 0.1 kg (Neviani, 1921). 



Bur-Gheluai does not appear on any maps available to us, but 

 the statement that it is 70 km from Bur-Hacaba and 80 km from 

 Baidoa places it at approximately 3°N, 44 °E, or about 200 km north- 

 west of the capital city of Mogadishu. 



Since a complete chemical analysis of this meteorite is lacking, we 

 have decided to remedy this, using a piece from a 1.3 kg stone (no. 

 778) in the collection of the U.S. National Museum. 



Mineralogical composition and structure. — The principal min- 

 erals are olivine, pyroxene, and nickel-iron (kamacite and taenite). 

 The usual amount of troilite is present as well as a small amount of 

 plagioclase. Accessory minerals include chromite and merrillite. 

 Prof. P. Ramdohr (pers. comm.) has examined a polished surface 

 and reports the occurrence of small amounts of native copper and 

 ilmenite, plus a trace of pentlandite. 



Olivine: The refractive indices are a = 1.670, 7 = 1.708, indicating 

 a content of 19 mole percent of the Fe 2 Si0 4 component, according to 

 the determinative curve of Poldervaart (1950). This was confirmed 

 by the X-ray method of Yoder and Sahama (1957). 



Pyroxene: Judging from optical and X-ray examinations, the 

 pyroxene is a mixture of bronzite and clinobronzite in approximately 

 equal amounts. The bronzite grains are transparent and untwinned, 

 and their refractive indices are a = 1.672, 7 = 1.682, indicating a 

 content of 16 mole percent of the FeSi0 3 component, according to the 

 determinative curve of Kuno (1954). The refractive indices of the 

 clinobronzite are approximately the same as those of the ortho- 

 pyroxene, but the grains are turbid, and optical properties are diffi- 

 cult to measure. 



Plagioclase: This mineral is fine grained, and only a mean re- 

 fractive index, about 1.538, could be measured, which indicates a 

 composition of about An J2 . 



A cut surface of the Bur-Gheluai meteorite is pale gray in color, 

 with numerous silvery-white metal particles. The metal particles are 



