346 The American Geologist. June, 1904. 
The monoclinic pyroxene, diopside, is idiomorphic, and con- 
tains many inclusions ; alteration to serpentine, chlorite, and 
amphibole is seen. The crystals have a maximum length of 
1.4 mm. and a width of .6 mm. 
Hornblende, both primary and secondary, was observed ; it 
is panidiomorphic with a maximum length of 1.5 mm. and a 
width of .6 mm. 
The biotite has no distinct form, but occurs in irregular 
patches. Magnetite is also present and the groundmass is com- 
posed of hornblende, biotite, and feldspar. 
SUMMARY AND CONCLUSION. 
It will be observed from the foregoing descriptions that the 
rocks of the Rossland district have a certain general relation- 
ship with each other. The kersantytes, camptonytes, minettes, 
and vogesytes, all have a lamprophyric structure; the kersan- 
tytes and minettes are both biotite bearing, the former having 
plagioclase feldspar in predominance over the orthoclase, while 
the latter has the proportions of the two feldspars reversed. 
The camptonytes and vogesytes are augite and hornblende 
bearing rocks having these two constituents generally in ex- 
cess over the feldspars ; the camptonytes contain more plagio- 
clase feldspar than orthoclase, while the vogesyte contains a 
greater amount of quartz and orthoclase than plagioclase. 
While only the typical lamprophyres have been described in this 
paper, the writer has found various gradations of these lam- 
prophyres into one another. 
The occurrence of these lamprophyres in America is rare ; 
a kersantyte has been (described from Minnesota.''' Dikes of 
kersantytes, vogesytes and minettes were found in the Little 
Belt mountains of Montana, t and at Franklin Furnace, Sussex 
county. New Jersey, $ and at Castle mountain, § Montana, and 
camptontytes were found at Campton Falls, New Hampshire, || 
and in the Lake Champlain region.^ Small dikes of campton- 
*N. H. WiNCHELL, The Geological and Natural History Stiriei/ of Miti- 
nesota, 1898-1900, vol. 5. 
tW. H. Weed. ZOth Annual Report, U. 8. O. S., Pfl-rt 3, Washington, 1898- 
99, pp. 538-545. 
tJ. S. DiLLBR, Bulletin 150, U. S. O. 8., Washington, 1898, pp. 236-238. 
SW. H. Weed and L. V. Pirsons, Bulletin 139, U. 8. O. 8., Washington, 
1896, pp. 110-114. A 
||J. S. DiLLER, Bulletin 150, U. S. O. 8., Washington, 1898, pp. 238-240. 
1[J. F. Kemp and V. F. Marsters, Bulletin 107, U. 8. G. 8.. Washington, 
1893, pp. 29-32. 
