Cincinnati Society of Natural History. 



crystals with the faces; OP (001), P (in), P (no), to which 

 are sometimes added xPx (010) and 3P3 (131). They are 

 usually broad and stout, and form inclusions in the quartz and 

 tourmaline. In a few instances they show a zonal structure. 

 In these zircons occur, as inclusions, a dark mineral, probably 

 magnetite, and small colorless lath-shaped crystals like those 

 which Thiiraeh found and showed to be apatite by isolation 

 and treatment with ammonium molybdate, an observation 

 that is interesting in showing the apatite to be older than the 

 zircon. Crystals of this mineral, free from inclusions, are 

 rare in these residues. A number of crystals are represented 

 in Figure 6. Other minerals, which occur in these northern 

 granite residues, are sphene, allanite, garnet and magnetite in 

 good crystals. The latter mineral is so abundant in many of 

 the residues that it obscures the other minerals unless removed 

 with a magnet. 



In the quarry at Port Deposit a considerable amount of 

 powdered rock was obtained from under the sieves of the 

 stone crusher, and its residue after washing contained zircons 

 in large number with the apatite inclusions, also allanite and 

 garnets. 



A striking peculiarity of the garnets obtained in these 

 granitic residues, especially in those of Port Deposit and 

 Perryville, is a more or less pronounced cubic form. While 

 many garnets show the common dodecahedron, with no other 

 planes in combination, these crystals offer a distinct contrast 

 in their hexahedral development. Their faces are never 

 sharp planes, but are more or less rounded, as though by a 

 tendency to the development of the tetrahexahedron, as 

 shown in Figure 6. When the extreme rarity of cubic faces 

 on garnets is considered, this occurrence seems worthy of 

 special note.* 



On account of the interest attached to the staurolite mica- 

 schist zone, it was also thought advisable to make a study of 

 the sand and soil near it. The residue, after the washing, 

 contained a large number of minerals. Hemimorphic crystals 

 of tourmaline of varying size were especially prominent. 

 Some of these crystals were small and stout, being nearly 



I am informed by Professor Derby that he has discovered similar cubic garnets 

 in the granitic residues which he has washed in Brazil. 



