sideromelane

plural sideromelanes

1. geographyA basaltic glass often found in palagonite tuff.

   In younger deposits, irregular patches of black fresh glassy sideromelane occur as “islands" coated by brownish palagonite envelopes of varying thickness.

   2012, Richard V. Fisher, Pyroclastic Rocks

   2 more examples

   The Korite is a hydrous labradorite; it is in dull brown grains, and is associated with Sideromelane, which has the same composition excepting the absence of water.

   1854, James Dwight Dana, A system of mineralogy, comprising the most recent discoveries

   The crystallization sequences observed in the one-atmosphere melting experiments are summarized in Table 16, where they are compared with the crystallization sequence deduced from petrographic examination of nearly holocrystalline rocks and of naturally occurring materials (which contain 80-95% glass), such as near-vent sideromelanes and dike selvedges.

   1978, Rosalind Tuthill Helz, The petrogenesis of the Ice Harbor member, Columbia Plateau, Washington