; de 
306 GEOLOGY. 
the prism becomes developed. According to M. Durocher,! in a memoir upon metamorphism, 
the four bands of the black material, placed in the diagonals of tke prisms, are formed of the 
same substance as the argillaceous schist which penetrates the interior of the crystal. This 
material preserves its schistose structure, and the films are disposed in the same plane as in the 
adjacent rock. The crystals would thus appear to result from the metamorphism of the 
elements of the schist, they being gradually replaced by a more compact and vitreous substance, 
Dufrénoy considers that the crystals of macle are the result of igneous action upon sedimentary 
beds, and states that the most perfectly formed crystals are found near the intruded igneous 
rocks, while at a distance from them the crystallization "becomes indistinct and the prisms 
appear to pass gradually into the mass of the surrounding rock. He also states that fossils 
have been found in the midst of schists containing well developed macles. These fossils show 
the sedimentary origin of the beds, and the macles indicate subsequent metamorphism. 
According to Dufrénoy, the two materials which compose the macles are essentially different; 
the white portions being hard enough to scratch glass, and infusible before the blow-pipe; the 
black material is easily scratched by a steel point, and is fusible to a black glass. 
The specimens which I have obtained, with one or two exceptions, have not the usual hard- 
ness ; they appear to be changed by long exposure. Nearly all of them are easily scratched by 
a knife, being nearly or quite as soft as calc-spar ; crystals which were found in the stream, and 
are translucent, are equally soft; but one of a flesh-red or rose color from the conglomerate 
scratches glass. 
Crystals of macle have the specific gravity 2.94 to 3. The chemical composition is identical 
with andalusite. M. Bunsen has analyzed the white portions of a specimen from Lancaster, 
Mass., with the following result: 
Silica . 39.00 
Alumina.. p 58. 56 
Oxide of manganese. . - 0. 53 
Lime "ner 0. 21 
98.30. 
The specimens from the Chowchillas are unusually large, and present a great variety ot 
interesting figures, and these being formed by dark lines on a nearly white or drab-colored 
ground are more striking and interesting than those from the well-known locality of Lancaster, 
Massachusetts. It would be interesting to the mineralogist to visit the original source of the 
specimens ; they must be very abundant, as they now form a not inconsiderable part of the 
conglomerate which covers the hills. Some interesting developments regarding metamorphism 
also undoubtedly await the explorer. x 
According to M. Dufrénoy* this curious mineral was observed for the first time by Comm: 
Bournon in the mountains of Forez, France. It was afterwards found at Andalusia, in Spain, 
whence its name, and it has since been obtained at numerous localities in Europe, but always in 
analogous positions. Fine crystallizations occur in the valley of Lisenz, near Inspruck, = the 
Tyrol, and at Westford, Massachusetts. It is found in fine specimens at Lancaster and Sterling; 
Mass. ; at Bellows Falls, Vt.; Charlestown, N. H.; Litchfield and Washington, Conn. ; and 
in Maine. Bs 
! Compte-Rendus de Y Académié des Sciences, xxii, 923, June, 1846. 
* Traité de Mineralogie, iii, p. 229, Paris, 1847. 
