chloropal

plural chloropals

1. chemistryA massive mineral, greenish in colour and opal-like in appearance, essentially a hydrous silicate of iron.

   Several delessites and chloropals occurring in basalts have a composition very close to that of the glass.

   1905, B. K. Emerson, “Plumose diabase and palagonite from the Holyoke trap sheet”, in Bulletin of the Geological Society of America, volume 16, page 105

   2 more examples

   A careful consideration of the various analyses of minerals of the chloropal group given by Dana, leads me, therefore, to propose that the following species and varieties should be regarded as a series of types to which all future discoveries in the group may be referred.

   1877, J. H. Collins, “Remarks on Gramenite from Smallacombe, and on the Chloropal Group of Minerals”, in The Mineralogical Magazine and Journal of the Mineralogical Society, page 70

   Nontronite, a variety of chloropal occurs as a light yellow powder in druses of the North Conway granite (99, p. 312).

   1969, T. R. Meyers, The Geology of New Hampshire: Minerals and mines, page 18