Hypocrystalline – crystals + glass
glassPlane light
X polarized light
Holocrystalline – 100% crystals
0 5 10 mm
Fine-grained (<1 mm)
Medium-grained (1-5 mm)
Coarse-grained (5-30 mm)
Aphanitic
Phaneritic
1mm
1mm1mm
Equigranular Seriate/Hiatal
Porphyritic
Plagioclase Porphyritic or Plag-phyric
Subhedral AnhedralEuhedral
Subpoikilitic PoikililticAmeboidalOikocryst Chadacyrst
Embayed Skeletal
Spinifex Dendritic Radial
Intergranular Subophitic Ophitic
Intersertal Pyroclastic
glass
olivine
Philip Farquharson, 2004 www-odp.tamu.edu/
Foliation – alignment of elongate minerals in a common plane
Qualifiers: Non-foliated – random orientation of elongate minerals
Poorly foliated – less than 50% aligned within 10° of common plane
Moderately foliated – 50-75% aligned “
Well foliated - > 75% aligned “
Trachytoid – alignment in fine-grained volcanic rocks
Radiate
Micrographic/GranophyricSutured Symplectitic
Corona
Biotite on Oxide Hornblende on Orthopyroxene Clinopyroxene on Olivine
Rapakivi - Alkali Feldspar mantled by Plagioclase Feldspar
Peritectic Reaction RimOl+melt = Opx
Exsolution in Inverted Pigeonite
< Blebby
Lamellar >
Linked Exsolution between Inverted Pigeonite (IP) and Augite (Cpx)
IP
IPBio
Feox
Cpx
Perthite – Na-plagioclase exsolved from K-feldspar
Oxide Needles in PlagioclaseOxide Exsolution and Epitaxial Biotite in Augite rimming Olivine
Plagioclase SymplectitePl>CaPl+Opx
Olivine Symplectite
Ol>Opx+Mt
Simple Twin (in Cpx) Polysynthetic Twinning(Albite Twinning in Pl)
Textural and Modal Layering in Gabbro Flow banding in Rhyolite
Amygdules in Basalt