CHAPTER X.
	Chiastolite, Cyanite, Datolite, Staurolite, Isopyre, Pectolite, Dioptase, Prehnite, Zono-chlorite, Chlorastrolite, Thomsonite, Lintonite, Natrolite, and Fluonte.
	T HE curious, cross-like markings of chiastolite (made) have suggested its use for gem purposes. The illustration shows the many markings that may exist in differ­ent parts of one crystal, and the variety of ornamental effects that may be produced. It is used for a gem, and sold for that purpose abroad, but there is no demand for it in the United States. Chiastolites are found in Mariposa County, Cal., and at Lancaster and Westford, Mass. William P. Blake first observed this mineral in Mariposa, where, in the drifts of the Chowchilla River, near the old road to Fort Miller, he found crystals in great
	abundance, showing the black crosses on the white ground in a remarkably perfect manner. They are also found in the stratum of conglomerate which caps the hills above the streams, and they were all doubtless originally in place in the slates a little higher up the river. Smaller and imperfect " macles " are found in the slates on the road to Bear River, at Hornitos, Cal. The Massachusetts localities have yielded many of the best specimens found. 175