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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 - click for larger pic
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".*



Minerals found in igneous breccias
Actinolite
Aegirine
Albite
Analcime
Anatase
Ancylite-(Ce)
Arsenopyrite
Ashcroftine-(Y)
Barite
Bastnäsite-(Ce)
Biotite
Brookite
Calcite
Carbocernaite
Catapleiite
Cerussite
Cordylite-(Ce)
Donnayite-(Y)
Elpidite
Epididymite
Eudialyte
Eudidymite
Ewaldite
Fluorapatite

Fluorapophyllite
Fluorite
Gaidonnayite
Galena
Ganophyllite
Gismondine
Gonnardite
Harmotome
Joaquinite-(Ce)
Kainosite-(Y)
Labuntsovite
Lead
Leucosphenite
Lorenzenite
Magnesio-hornblende
Mangan-neptunite
Microcline
Millerite
Molybdenite
Monteregianite-(Y)
Narsarsukite
Natrolite
Nenadkevichite
Paranatrolite
Parisite-(Ce)
Pectolite
Pyrite
Pyrophanite
Pyrrhotite
Quartz
Richterite
Rutile
Sodalite
Sphalerite
Steacyite
Stillwellite-(Ce)
Strontianite
Synchysite-(Ce)
Tadzhikite-(Ce)
Tainiolite
Thomsonite
Titanite
Vinogradovite
Wulfenite
Xenotime-(Y)
Yofortierite
Zircon

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