Ophiolite
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An ophiolite is a section of Earth's oceanic crust and the underlying upper mantle that has been uplifted and exposed, and often emplaced onto continental crustal rocks.
Ordovician ophiolite in Gros Morne National Park, Newfoundland
Chromitic serpentinite, Bay of Islands Ophiolite, Lewis Hills, Newfoundland
A simplified structure of an ophiolite suite: axial magma chamber pelagic sediments pillow basalts sheeted basaltic dykes intrusive, layered gabbro dunite/peridotite cumulates
Classic ophiolite assemblage in Cyprus showing sheeted lava intersected by a dyke with pillow lava on top.
Serpentinite
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Serpentinite is a metamorphic rock composed predominantly of one or more serpentine group minerals formed by near to complete serpentinization of mafic to ultramafic rocks. Its name originated from the similarity of the texture of the rock to that of the skin of a snake. Serpentinite has been called serpentine or serpentine rock, particularly in older geological texts and in wider cultural settings.
Serpentinite from the Maurienne valley, Savoie, French Alps
Sample of serpentinite from the Golden Gate National Recreation Area, California, United States
Chromitic serpentinite (7.9 cm (3.1 in) across), Styria Province, Austria. Protolith was a Proterozoic-Early Paleozoic upper mantle dunite peridotite that has been multiply metamorphosed during the Devonian, Permian, and Mesozoic.
Tightly folded serpentinite from the Tux Alps, Austria. Closeup view about 30 cm × 20 cm (11.8 in × 7.9 in).