Page:The Geologist, volume 5.djvu/114

90 The mass is covered thickly with a series of shallow pits or depressions, about $1⁄8$ to $1⁄10$ of an inch deep. The spaces between the holes are bright like steel. Its weight is about 12 or 13 lbs.

In consequence of finding a difficulty in fixing the position or positions of the Atacama Meteorite in 1826, I gave Peine, Guanaquero, Chala, and two other spots north of Challa, all in the desert of Atacama; also Miño, to the east of Mani, near the Peruvian and Bolivian boundaries. I tried to get across the desert in 1828, from the coast of the Pacific, in the hope of examining the localities of Guanaquero and Peine, near to one or other of which places I hoped to find the meteoric deposit. I was lost for awhile in the desert of Atacama, and had to return to the coast. Near to Toconao. north-east of Peine, was supposed by Sir W. Parish to be the spot; but in 1853, Dr. Philippi determined Imilac, a few miles south-west of Peine, to be the spot, or one of the spots of the fall of the Atacama Meteorite.

A. very large specimen from Atacama is in the possession of Domeyko, in Santiago, in Chile; some others I have seen, as well as many small fragments which fell at Imilac; as to my small specimen obtained in 1826, when I was in Tarapuca, it may or may not have been collected at Imilac.

The large specimen of the Atacama Meteorite deposited by me in the British Museum, I procured on the west coast in 1854. I have had some doubts as to whether Imilac ought to be given as the locality of its fall. I made this observation in my paper to the Meteorological Society, 1858, as to this specimen; the same will apply to a slice of meteoric stone in the same Museum, and that in the Museum of Practical Geology. The information I had was what I let the British Museum have, that it (and others, one weighing over 50lbs.) were brought to Cobija by a muleteer, from "somewhere to the east in the desert of Atacama, and it was thought there were several similar deposits in the track to Antofogasta."

These specimens have the external mechanical character of the Imilac specimens, but the metallic part is dark, as if much oxidized, and the earthy part is more crystalline.

Nicol, in his 'Mineralogy,' gives an analysis by Rivero of meteoric iron from "Potosi:"—iron, 90⋅24; nickel, 9⋅76 = 100⋅0. Domeyko gives for the Atacama one (Imilac):—iron, 88⋅54; nickel, 8⋅24; cobalt, 1⋅14; silica, 0⋅16. From this difference of composition compared with that of the one from "Potosi," we may say that Imilac was not its place of deposit.

I advert in my paper to the Meteorological Society to three stones found four leagues inland from Playabrava (23° 35′), two round and porous, the other porous, flat, and triangular. I suspect them to be meteoric (for they are said to be of "iron"), and the locality they were found in, although near the latitude of Imilac, is much further to the west. Having disposed of these amygdalo-peridotic varieties,