PALACHE AND WOOD. CRYSTALLOGRAPHIC NOTES. 647 



line faces in a striated zone ; measurement of more crystals would prob- 

 ably increase their number, and they are variable in position. They 

 occur on crystals of type a. 



Corundum. Veins traversing the emery and containing massive 

 corundum have long been known and are well described by Emerson. 4 

 One such vein, about 2 cm. thick, was collected in 1904 which showed 

 the following minerals symmetrically developed on the two walls: 



1. Ilmenite in thin plates with thin films of chlorite along parting 

 surfaces. 



2. Alternating thin layers of margarite and corundophyllite, the latter 

 also projecting into the vein in larger crystals. 



3- Rich blue corundum forming the vein centre without open spaces. 



Where the corundum-bearing veins are filled at the centre by calcite, 

 crystals are not seldom developed, generally with rounded or rough 

 faces and not measurable. One tiny veinlet in chlorite, however, 

 yielded us exquisite crystals of pure sapphire blue color, transparent 

 and with symmetrical faces, brilliantly lustrous. Although minute, the 

 crystals gave good measurements for the following forms : r (10T1), 

 s (0221), n (2243), and h (33(51). The last named is new and is es- 

 tablished by the following angles measured on two crystals with the 

 two-circle goniometer : 



This form is recorded by Melczer 5 who observed it on ruby crystals 

 from Burmah as one of a series of weak images given by rounded por- 

 tions of the crystals. He did not regard the form as established, but 

 only as indicated. 



Figure 8 shows the observed combination with little alteration of the 

 actual proportions. The crystal figured was about 1.5 mm. in length. 



* Loc. cit., Monograph, 29, p. 144. 



6 Melczer, G. Zeitschr. fur Kryst., 1901, 35, 570. 



