DE. W. FLIGHT, GREENLAND METEORITES. 457 



the rapidity with which the oxidation of the pulverised mineral 

 takes place : five days after the analysis Avas made the per-centage 

 of iron-protoxide in another portion had fallen to 3 '47, and after 

 three weeks to 1 '55. The original unchanged mineral was pro- 

 bably a hydrated ferrous silicate. 



The following rocks from Disko island have been examined by 

 Nauck hoff : 



I. Section of a six-sided basalt column from Erededal, east side 

 of Skarfvefjell and about 10' E. of Godhavn ; showing compact 

 dark greyish-green ground-mass with crypto-crystalline texture ; 

 under the microscope, crystals of a felspar, augite, and magnetite 

 are recognised. Fusible before the blow-pipe.— II. Basalt from 

 the east side of the ridge at Ovifak, Avhere the iron and breccia 

 were found. Fusible before the blowpipe. — III. Rock occurring 

 in rounded masses, with green foliated crust, in the basalt ridge, 

 and inclosing spangles and spherules of iron, some 6 — 7 mm. in 

 diameter ; these exhibit Widmannstattian figures. Appears to be 

 a very finely granular mixture of a felspar with a small amount of 

 a green mineral, probably augite, and imperfectly crystallised 

 magnetite, which latter usually surrounds the spangles of iron ; 

 olivine is only occasionally met with, in grains the size of a pea. 

 Melts with dilficulty before the blowpipe. — IV. Very hard brown- 

 coloured mass inclosing rock in which iron spangles are found ; it 

 closely resembles III. The ground-mass consists of a felspar, 

 probably anorthite, the crystals of which are occasionally large, 

 and show marks of twinning, and a great number of reddish 

 octahedra closely resembling spinel. Small particles of a greenish 

 mineral, having the appearance of augite, are also to be distinguished. 

 Spangles of iron are very rarely found in the felspar ; and magne- 

 tite is apparently absent. Melts very slowly before the blowpipe. 

 — V. Rounded lump of grey rock from the basalt ridge ; it was 

 covered with a dark-green vesicular crust, from 15 to 20 mm. 

 thick. Through the ground-mass, which appears to consist of a 

 felspar, were disseminated numerous brilliant greyish scales, 

 besides some very black magnetite or graphite. Augite sparsely 

 distributed ; abundance of red spinel in some parts, none in 

 others. Melts with great difficulty before the blowpipe. — VI. 

 The dark greenish-brown crust of V., closely resembling that 

 of the rounded masses III. It consists of a felspar inclosing a 

 brown and a green augite-like mineral, and, in places, clusters of 

 granules of spinel. Melts with great difficulty before the blowpipe. ■ 

 — VII. Light-grey foliated rock from Ovifak, the exact circum- 

 stances of the occurrence of which are not known. The ground- 

 mass consists of a mixture of a felspar with a grey, finely foliated 

 mineral with graphitic lustre. Red spinel is met with abundantly in 

 both constituent minerals. This variety of rock, like those from the 

 ridge, is covered with a rust-like crust. It breaks easily, and always 

 parallel to the scales. Before the blowpipe it melts with difficulty 

 on the edges. — VIII. Compact, slightly weathered breccia, filling 

 a fissure two to three inches wide in the basalt ridge parallel to 

 which it runs. It is a black granular mass, devoid of metallic 

 lustre, and incloses fragments, some witli edges sharp and angular 

 others with the corners rounded, of a rock exactly like that form- 



