132 FIELD CoLuMBIAN Mus—EuM—GEo_oGy, VoL. III. 
by this peculiarity and thus the orientation of the crystal is much 
facilitated. These striations are probably the result of oscillation of 
the plane a (100) with prismatic planes, and in some crystals, as 
shown in Fig. 3, Pl. XLVI, this is obviously the case. 
As is usual with anglesite, the crystals exhibit a variety of habits, 
no single habit predominating. The habits noted may be described 
as tabular, prismatic, and pyramidal. Of these perhaps the most 
striking and unusual to anglesite is the tabular one. It is produced 
by a pronounced development of the basal planes uniting with a short 
unit prism. Figs. 2 and 3, Pl. XLV, showing crystals taken from 
specimens having the Museum Numbers M 9579 and 7293, illustrate 
the habit. Crystals of this type may be simple or highly modified. 
In some the prism becomes longer in the direction of the vertical 
axis, as shown in Fig. 3, Pl. XLV. Crystals of this type are usually 
attached by one of the planes of the unit prism so that their orienta- 
tion is not always obvious at a glance. 
Prismatic habits are common and, as is usual with anglesite, the 
habit may be produced by elongation in the direction of either of the 
axes. Crystals elongated in the direction of the vertical axis are 
illustrated in Fig. 4, Pl. XLV (Mus. No. M gs90) and Fig. 1, Pl. XLVI 
(Mus. No. M 9586). Of these No. M gs5g0 is from the Bullion Beck 
mine. It exhibits the peculiarity of having the prism m (110) at 
one end of the crystal and the prism 6 (230) at the other. As illus- 
trated in the figures, the crystals of the vertically elongated prismatic 
habit may have pointed or blunt terminations. The blunt termina- 
tion is produced by broad development of the basal plane and gives an 
especially characteristic form (Fig. 1, Pl. XLVI). Crystals elongated 
in the direction of the brachy-axis are illustrated by Fig. 2, Pl. XLVI 
(Mus. No. M 9587). Crystals of this type are inclined to stoutness. 
They are semi-transparent and have the planes well developed. 
The finest crystal of the whole collection exhibits this habit, the elon- 
gation in the direction of the brachy-axis being, however, less than 
shown in the figure of the type. This crystal has a length of 2 centi- 
meters in the direction of the vertical axis and 1.5 centimeters in the 
direction of the macro-axis. It is perfectly transparent and colorless. 
Another superb crystal of this habit has a well-marked canary yellow 
color. It is about three-fourths the size of the one previously men- 
tioned. 
Fig. 3, Pl. XLVI (Mus. No. M 9582) shows a crystal form in which 
the elongation occurs in the direction of the macro-axis. Crystals of 
this type are as a rule small, having a maximum length of about 1.5 
