Porphyritic Basalt

Type	Igneous Rock
Texture	Porphyritic
Origin	Extrusive/Volcanic
Chemical Composition	Mafic
Color	Dark Gray to Black
Mineral Composition	Calcium Plagioclase, Pyroxene
Miscellaneous	Calcium Plagioclase phenocrysts in an aphanitic (Fine-grained) groundmass
Tectonic Environment	Divergent Boundary or Intra-oceanic hot spots