Mr. Skey announced in 1885 the discovery of terrestrial nickel-iron in New Zealand. Grains of the alloy (Awaruite), containing as much as 67·6 per cent. of nickel, are found in the sand of the rivers flowing from a range of mountains composed of olivine-enstatite rocks, in places altered to serpentine: similar particles have been found in the serpentine itself. Similarly, in the sand of the stream Elvo, near Biella, in Piedmont, and of the river Fraser, British Columbia, grains of nickel-iron containing 75 or 76 per cent. of nickel have been found: and in the placer gravel of a stream in Josephine and Jackson Counties, Oregon, U.S.A., large quantities of waterworn pebbles, which enclose an alloy (Josephinite) of nickel and iron containing 72 per cent. of the former metal, have been met with. Professor Andrews many years ago established the presence of minute particles of metallic iron in some basalts; Dr. Sauer has lately found a single nodule of malleable iron of the size of a walnut in the basalt of Ascherhübel, in Saxony; Dr. Hornstein has described large nodules of (nickel-free) iron found in basalt in a quarry at Weimar, near Cassel; Dr. Beckenkamp has described nodules of metallic iron found in clay at Dettelbach, near Würzburg; and Dr. Johnston-Lavis has announced the find of an enclosure of metallic iron in a leucitic lava of Monte Somma; Dr. Hoffmann has noted the occurrence of minute spherules of brittle iron both in perthite and quartzite in Ontario; Dr. Hussak has recorded the discovery of metallic iron in an alluvium of Brazil, and Dr. Högbom has found it associated with topaz, quartz, felspar, and other minerals, in limonite from an unspecified place in South America; two minute grains of iron were found by Mr. Osaka in the débris of an agglomerate at Nishinotake, Japan.
The stony matter of meteorites.
46. The stony part of the siderolites and aerolites is almost entirely crystalline, and in most cases presents a peculiar "chondritic" or granular structure, the loosely coherent grains being composed of minerals similar to those which enclose them, and containing in most cases minute particles of iron and troilite disseminated through them: glass-inclusions are found to be present. The minerals mentioned above as occurring in meteorites are such as are very characteristic of the more basic terrestrial rocks, such as dunite, lherzolite and basalt, which have been expelled from considerable depths below the earth's surface.
47. Several attempts to classify aerolites according to their mineralogical constitution have been made, but it cannot be said that any of them is very satisfactory; seeing that even in the same stone there may be much difference in its parts, a perfect classification on such a basis is scarcely to be hoped for.
Chondritic aerolites.
About eleven out of every twelve of the stony meteorites belong to a division to which Rose[22] gave the name of chondritic (chondros, a grain): they present a very fine-grained but crystalline matrix or paste, consisting of olivine and enstatite or bronzite, with more or less nickel-iron, troilite, chromite, augite and anorthic felspar; through this paste are disseminated round chondrules of various sizes (up to that of a walnut) and with the same mineral composition as the matrix; in some cases the chondrules consist wholly or in great part of glass.[23] In mineral composition chondritic aerolites approximate more or less to terrestrial lherzolites. Some meteorites consist almost solely of chondrules, others contain only few; in some cases the chondrules are easy separable from the surrounding material. Of the chondritic division Knyahinya, Pegu, Muddoor, Seres, Pane 4n. Judesegeri, Khiragurh, Utrecht and Nellore (pane 4p) afford good illustrations.
A carbonaceous group.
A few meteorites belonging to this division are remarkable as containing carbon in combination with hydrogen and oxygen. Of these the Alais and Cold Bokkeveld meteorites Pane 4n. are good examples: the former has a bituminous smell; it yields sulphates of magnesium, calcium, sodium and potassium, if steeped in water.
Aerolites without chondrules.
Pane 4o.