128 Ichikawa — Notes on Japanese Minerals. 



on the new faces; in G a gronp of laniellated trigonal 

 plates are shown. The angles are: C(abc)=110°; 

 D(abc)=90°; D(adc)=110°; E(abc)=65°. 



It is shown here that the sides of the trigonal plates 

 (E, F, G, etc.) on the face mR and those of the natural 

 pits (d, e, f, etc.) on the trigonal planes are parallel to 

 the rhombohedral cleavage (see cross-striations in A). 

 The reader must compare the natural pits of d, e, f, etc. 

 on E, F, G, etc. with those in mR of II; see also this 

 Journal, vol. 42, pp. 114, 1916. Figure 2 shows a new 

 rhombohedral form formed on — y 2 R of figure 1, A and 

 the natural depressions on its faces. Figure 3 shows the 

 etching of a cuboid calcite crystal found in a Tertiary 

 tuff at Maruyama, Echizen. A is a front view (X 10). 

 On the rhombohedral faces trigonal pits are found, and 

 on the scalenohedral faces striations are noted. B shows 

 a cleavage fragment (R) with depressions formed by 

 etching. 



Fig. 4 shows the etching of a scalenohedral crystal 

 (with cleavage face) found in the zincblende mine at 

 Nerimata. A is a* front view ; B shows the natural depres- 

 sions formed on a cleavage face of A; the angles are: 

 abc = 112°; adc = 100°; compare also figure 1, D (II) 

 and figure 4, B (I). Figure 5 shows the etching of a 

 scalenohedral crystal also from a crystalline limestone at 

 Kami5mushi. The face mR is depressed in the direc- 

 tion of longer diagonal by etching. B shows the relation 

 between the outline of the natural depression and the 

 edges, striation, etc. of the face (mRn) : the angles are: 

 abc = 110°; bed = 105°; cda = 30°. The direction of 

 cb in the depression is parallel to the striations on the 

 face. C and D also are natural depressions observed on 

 the same face; the angles in D are: abc = 60°; bad = 

 100°; adc = 100°. The direction of ab in D is parallel 

 to that of ab in B. 



Fig. 6 shows the etching of another scalenohedral crys- 

 tal from the same localitv. B shows the relation between 

 the outline of varieties of the natural pits and edges, stri- 

 ation, etc. of the face mRn. The line ab in the figure 

 shows a fissure in the direction of cleavage. Long ellip- 

 tic natural depressions on the face much resemble a part 

 (ab) of the natural depressions in figure 5, B. C shows 

 a trigonal pit on the face mR: the angle abc = 40°. 

 The symmetry of the etched figures shown in I and II 



