EC. 1908. MINERALOGICAL NOTES 153 
crystals in a parallel direction than the development of a single crystal. 
Nevertheless many of the planes give reflections like those of a single 
plane. The color of these crystals is a dark olive-green and they 
usually exhibit a radiated arrangement in their attachment. The 
individual crystals are attached by the end of the brachy-axis, their 
length averaging about 5 mm. The planes are as a whole bril- 
liant and give fair reflections. Fig. 5, Pl. LII, represents a habit 
tabular with respect toa (100). This habit is exhibited by the crystals 
of a single specimen, Mus. No. M 9403. These crystals are very small, 
their greatest length being .5 mm. and thickness .1 mm. They are 
also peculiar in being nearly transparent and having a pale olive- 
green color rather than the deep green to black usually characteristic 
of the mineral. The cavity in which the crystals occur is lined 
with chrysocolla, and upon this the olivenite is implanted. The 
above specimens are all from Eureka, Utah. A single specimen, Mus. 
No. M garg, from Mammoth, Utah, exhibits crystals differing some- 
what in habit from any of the above. This habit is shown in Fig. 6, 
Pl. LI, and is characterized by prominent development of the basal 
planes, and elongation in the direction of the macro-axis, producing a 
tabular form. A brachydome not previously noted on olivenite also 
occurs on these crystals. This lies between the base c (oor) and the 
unit dome e (o11) and its determination is based upon its occurrence 
mete zoue noted and the measurement'e A. s = 7° so’. Occur- 
ring with crystals of this habit are others of the habit shown in Fig. 
2,Pl. LIT. All the crystals on this specimen, Mus. No. M gq41g, are 
greenish-black in color, opaque, and have brilliant planes. They 
occur encrusting cavities in massive malachite. 
In the measurement of the crystals as a whole it was found that 
the angles observed did not agree with those obtained from the axial 
ratios of Washington as fully as could be desired. This discrepancy 
was especially noticeable in the measurement of the prism m A m”’. 
A large number of measurements of this angle gave a value closely 
approximating 87° 28’, which differs nearly a degree from that 
obtained by Washington, his value being 86° 26’. Further, the 
measurement obtained for e A e’, approximated in several good 
measurements closely to the value 69° 18’. These values agree more 
closely with the measurements of Phillips * than with thoseof Washing- 
ton. The excellence of the measurements on the Eureka crystals 
seemed to warrant the calculation of axial ratios from them, and these 
* Mineralogy, 1823, p. 319 
