E. S. Dana — Petrography of the Sandwich Islands. 459 



about the borders of the vesicles the iron is especially dense. 

 It is very interesting to note that these specimens are the 

 only ones among those from Kilauea which show distinctly 

 the stellate feather-like forms of the augite and feldspar so 

 characteristic of many of the Mauna Loa lavas (as shown in 

 fig. 1, d, p. 443). The augite forms here are usually smaller, and 

 less varied, but there is the same grouping in parallel bundles 

 diverging off at the ends into dendritic forms. The association 

 between the augite and feldspar is also very close, as if the 

 crystallization of the two had been almost simultaneous. Thus 

 the feldspar not only forms in some cases the outer extremities 

 of the feather but sometimes also is a central rib flanked on 

 both sides by the augite. 



Occasionally the chrysolite appears in the long slender forms 

 noted as common among the Mauna Loa lavas. One of these 

 is shown in figure 4, k, which also exhibits the peculiar feature 

 of many of these rocks — often noted in other regions* — the 

 grouping of the titanic iron in parallel position about the chrys- 

 olite, normal to the vertical axis. An arrangement of the 

 elongated forms of the titanic iron in parallel position over 

 small areas is sometimes noted where there is no evident rela- 

 tion to the other constituents. Usually, however, the chryso- 

 lite is the controlling influence and the individual often bristles 

 with these little iron rods about its whole outline as seen in the 

 section. Although these specimens were taken from so near 

 the glassy crust there is little or no glass shown in the thin 

 section. A specimen from the bottom of the Little Beggar, 

 the lowest part of Kilauea, shows very considerable alteration, 

 the surface being covered and the vesicles filled with crystals 

 of gypsum ; the mass is rendered red and nearly opaque by 

 the oxidation of the iron. 



A specimen of partially devitrified glass shows the presence 

 of spherulites, like those mentioned in similar specimens from 

 Mauna Loa, increasing in number where the devitrification is 

 most complete. Crystals of chrysolite and microlites of feld- 

 spar are also present in large numbers. Some curious specimens 

 from the spatterings about a biow-hole exhibit a vesicular glass 

 with crystals of chrysolite and aggregates of augite and feld- 

 spar. The chrysolite encloses large amounts of glass, often in 

 curiously arranged symmetrical bands. One of the crystals is 

 represented in fig. 4, I. 



2. The older lavas. — Of the ancient Kilauea lavas, one speci- 

 men from Waldron's Ledge (13) is remarkable for its highly 

 chrysolitic character, as its unusual density (Gk = 3-18) well 

 shows. It is a grayish compact rock thickly sprinkled with 

 greenish yellow chrysolite grains. Under the microscope the 

 chrysolite is seen to be in large individuals, usually irregular 



* Cf. Rosenbusch, Mass. Gesteine, p. 722, 1887. 



