Neoblast Crystal grain in a metamorphic rock
Normal fault Also called a slump fault, is a fault in which the hanging wall
appears to have moved downward in relation to the footwall
Pangaea Large landmass, considered as being the original continent that has
existed for 200 million years and included all the continents we see today
Peridotite alteration Chemical reaction during serpentinization (alteration) of
peridotite in the presence of water: Peridotite þ 2H 2 O ¼ Mg
2þ þ SO 2 þ
H 2 O 2Mg 2 SiO 4 forsterite
ð
Þþ3H 2 O ¼ Mg 3 Si 2 O 5 OH
ð Þ 4 Antigorite
ð
Þþ MgO
OH
ð Þ Brucite
ð
Þ
Petrology Study of rocks by petrologists, who are scientists able to determine the
origin of rocks through a study of their mineralogy, texture, structure and
chemical composition
Phenocryst Large ([0.1 mm in diameter) crystal in a rock
Picritic basalt Type of basalt that is enriched in olivine (silicate of iron and
magnesium) minerals
Pillow mound Piling up of pillow lava flows found in all underwater volcanic
terrains
Plagioclase Mineral that is a silicate of aluminum, calcium and sodium
Platinoid The platinum group metals abbreviated as the PGM including: platinum
(Pt), osmium (Os), iridium (Ir), rhuthenium (Ru), rhodium (Rh) and palladium
(Pd). Alternatively called platinoid, platinum group, platinum metals, platinum
family or platinum group elements (PGEs)
Porphyritic Texture of an igneous coarse-grained rock, containing large sized
crystal grains or phenocrysts
Pyroclast Volcanic debris having a grain size more than 64 mm in diameter
extruded during explosive eruption. The name pyroclasts comes from the Greek
pyros meaning fire and klastos meaning fragment
Pyroxene Mineral made up of a silicate of aluminum, calcium, magnesium, and
iron
Pyroxenite Intrusive rock associated with peridotite that consists of clinopyroxene and orthopyroxene, with or without plagioclase. Pyroxentite is found
forming veins and lenses (0.3 up to 20 cm thick) that are variably serpentinized.
Also contains the minerals amphibole, spinel and ilmenite. They can be classified as being orthopyroxenite and websterite
Rheology The study of the deformation and flow of matter
Rhyodacite Silicate-enriched rock close in composition to granite
368
Glossary
Normal fault Also called a slump fault, is a fault in which the hanging wall
appears to have moved downward in relation to the footwall
Pangaea Large landmass, considered as being the original continent that has
existed for 200 million years and included all the continents we see today
Peridotite alteration Chemical reaction during serpentinization (alteration) of
peridotite in the presence of water: Peridotite þ 2H 2 O ¼ Mg
2þ þ SO 2 þ
H 2 O 2Mg 2 SiO 4 forsterite
ð
Þþ3H 2 O ¼ Mg 3 Si 2 O 5 OH
ð Þ 4 Antigorite
ð
Þþ MgO
OH
ð Þ Brucite
ð
Þ
Petrology Study of rocks by petrologists, who are scientists able to determine the
origin of rocks through a study of their mineralogy, texture, structure and
chemical composition
Phenocryst Large ([0.1 mm in diameter) crystal in a rock
Picritic basalt Type of basalt that is enriched in olivine (silicate of iron and
magnesium) minerals
Pillow mound Piling up of pillow lava flows found in all underwater volcanic
terrains
Plagioclase Mineral that is a silicate of aluminum, calcium and sodium
Platinoid The platinum group metals abbreviated as the PGM including: platinum
(Pt), osmium (Os), iridium (Ir), rhuthenium (Ru), rhodium (Rh) and palladium
(Pd). Alternatively called platinoid, platinum group, platinum metals, platinum
family or platinum group elements (PGEs)
Porphyritic Texture of an igneous coarse-grained rock, containing large sized
crystal grains or phenocrysts
Pyroclast Volcanic debris having a grain size more than 64 mm in diameter
extruded during explosive eruption. The name pyroclasts comes from the Greek
pyros meaning fire and klastos meaning fragment
Pyroxene Mineral made up of a silicate of aluminum, calcium, magnesium, and
iron
Pyroxenite Intrusive rock associated with peridotite that consists of clinopyroxene and orthopyroxene, with or without plagioclase. Pyroxentite is found
forming veins and lenses (0.3 up to 20 cm thick) that are variably serpentinized.
Also contains the minerals amphibole, spinel and ilmenite. They can be classified as being orthopyroxenite and websterite
Rheology The study of the deformation and flow of matter
Rhyodacite Silicate-enriched rock close in composition to granite
368
Glossary