Mineral Environments
- Igneous Breccia -

     "The igneous breccias consist of fragments of various rock types,
including hornfels, nepheline syenite, gabbros and pyroxenites usually
cemented by fine-grained albite. The rock fragments tend to be angular in
shape, and vary in size from a few centimeters to nearly 1 meter across.
Elongated, irregular cavities 5 - 15cm in length occur in the albite in the
interstices between the fragments, and contain a unique suite of superbly
crystallized minerals".*

Igneous breccia from MSH
© Quintin Wight

     In some breccia zones the rock fragments exhibit partial melting and reaction rims, and appear more rounded as a result of having been partially digested by the rising magma. Cavities are less common, smaller, or non-existent in this type of breccia".*

* From Mineralogical Record Vol 21, Horváth L. and Gault R.A.