Volcanic Disturbances in West Indies 293 



plagioclase, apparentl}' labradorite,with 

 augite, hypersthene, olivine, and mag- 

 netite. The single, large olivine grain 

 is not surrounded with hypersthene, as 

 in the other specimens, and one large 

 crystal of augite showing lamellar twin- 

 ning has an inclosed core of pleochroic 

 hypersthene in parallel cr\ _ stallographic 

 position. 



The olivine is evidently one of the 

 early products of crystallization, and it 

 is remarkable that three of the four 

 specimens from St Vincent contain oli- 

 vine. They recall to my mind lapilli 

 found among those of the final eruption 

 at Mount Mazama of Crater Lake, 

 Oregon, where olivine is an exceptional 

 constituent and not found in the dacitic 

 lava of the same eruption. 



No. 2. " Volcanic dust fell at King- 

 ston, St Vincent, May 7, 1902. Col- 

 lected May 24, 1902." The dust is 

 light gray and uniformly fine, as if well 

 assorted during its flight from the coarse 

 material ejected at the same time. The 

 largest particle measured had a diameter 

 of six-tenths of a millimeter. Many 

 mineral particles are five-tenths of a 

 millimeter in diameter, but the average 

 is not more than two tenths of a milli- 

 meter. 



The larger particles are of dirty glass, 

 rarely clear, and colorless and full of 

 bubbles. Others contain a multitude 

 of minute crystals. Those filled with 

 these microlites are of pulverized older 

 rock, while the dirty vesicular glass 

 ones like the groundmassof the pumice 

 represent the molten magma of the 

 eruption. The latter appear to be most 

 abundant. The greater portion of the 

 dust is crystal fragments of plagioclase, 

 augite, hypersthene, brown hornblende, 

 and magnetite. Olivine may be pres- 

 ent, but its presence could not be dem- 

 onstrated. 



No. 3. "Volcanic dust; surface of 

 deposit at Richmond House, St Vin- 

 cent. Collected May 25, 1902." The 

 material is just like that of No. 2 ex- 



cepting that some of the mineral frag- 

 ments are larger, reaching over a milli- 

 meter in diameter, the proportion of 

 microlitic groundmass particles greater, 

 and a grain of olivine was observed. 



SAND AND DUST FROM BARBADOS 



Beside the material collected by Pro- 

 fessors Hill and Russell on Martinique 

 and St Vincent, several specimens of the 

 sand and dust were obtained at greater 

 distances from the points of eruption. 

 Sand and dust fell at Barbados May 7 

 and 8, as described elsewhere,* to a 

 depth of three-fourths of an inch. It 

 was supposed by eyewitnesses to have 

 come from St Vincent, distant 90 miles 

 directly west. 



The largest particles have a diameter 

 of about six-tenths of a millimeter and 

 average half that size. The sand is a 

 mixture in which crystal fragments pre- 

 dominate over glassy particles. Plagio- 

 clase is most abundant. Hypersthene, 

 augite, and magnetite, and perhaps 

 traces of other minerals, occur. An 

 analysis of material from the same fall 

 in Barbados was made by Dr Pollard 

 and published by Mr J. J. H. Teall.f 

 It is given in the table of analyses. Mr 

 J. D. Falconer in the same journal re- 

 ports ' ' a very few crystals of brown 

 hornblende," and T. C. Porter mentions 

 dark-colored mica and olivine, but from 

 his description the latter is most likely 

 hypersthene. 



The presence of augite in consider- 

 able quantities supports the view ex- 

 pressed above that the sand came chiefly, 

 if not wholly, from L,a Soufriere, on 

 St Vincent. 



DUST FROM THE STEAMSHIP COYA 



The British steamship Coy a, on the 

 evening of May 7, encountered a shower 

 of volcanic dust 275 miles southeast of 



* Science, June 13, 1902, p. 947. 

 f Nature, June 5, 1902, p. 130. 



