362 



THE MAEQUETTE IRON-BEAKING DISTRICT. 



They thus occupy a horizon within tlie iron-bearing formation, and in a 

 number of cases they are between the griinerite-magnetite-schists or sideritic 

 slates below and the jaspilite above. The rocks here named ferruginous 

 chert are called liy the miners "soft-ore jasper," discriminating them from 

 the hard-ore jasper, or jaspilite. This material is so called because within 

 or associated with it are found the soft ores of tlie district. 



FlO. 22. — Jasjiil)!!' lit 111 ]iiil,lir miiif , shuwiTi^ wliiti' areas of chert in the red jasper. 



The jaspilites are rocks consisting of alternate bands composed mainly 

 of finely crystalline, iron-stained quartz and iron oxide (Pis. XXIV-XXVII, 

 and fig. 22). The exposures present a brilliant appearance, due to the inter- 

 lamination of the bright-red jasper and the dark-red or black iron oxides. 

 The iron oxide is mainly hematite, and includes both red and specular varie- 

 ties, but magnetite is frequently present. The jasper bands often have oval 

 tei'minations, or die out in an ii-regular manner. The folding, faulting, and 

 brecciation of the jaspilites are precisely like those of the ferruginous cliert, 

 except that in the jaspilite they are more severe. The interstices produced 

 by the dynamic action are largely cemented with crystalline hematite, but 

 magnetite is present in siibordinate quantity. 



