EASC 1002 Midterm Study

Igneous rocks

Formed from cooling lava or magma. no distinct layering or banding. Can be Intrusive or Extrusive.

Extrusive textures

Glassy, Aphaeretic (fine-grained), Amygdaloidal (Vesicles filled in), Vesicular (bubbly)

Intrusive texture

Phaneritic (large-grained)

Porphyritic texture

slow cooling followed by fast cooling. rocks usually contain larger crystals with a finer aphaeretic groundmass.

Igneous Textures

Extrusive, Intrusive, Porphyritic, Fragmental/Volcanic

Extrusive rocks

Rhyolite, Andesite, Basalt

Intrusive rocks

Granite, Diorite, Gabbro, Peridotite

Sedimentary Rocks

Comprised of clasts / grains of pre-existing rock or organic material which are then compacted and cemented together. Either are layered / banded or are homogenous

Clastic rocks

Composed of eroded, loose rock and mineral fragments from pre-existing rock that are cemented together after they are deposited

Organic Rocks

Made from the carbon-rich remains of living organisms and plants

Biochemical Rocks

Made from living organism. Typically shells or exoskeletons.

Chemical Rocks

Formed by precipitating out of a body of liquid

Types of Sedimentary Rocks

Clastic, Organic, Bio-Chemical, Chemical

Clastic Rock examples

Sandstone, Greywacke, Conglomerate, Breccia, Siltstone, Shale

Chemical Rock examples

Halite

Bio-Chemical Rock examples

Coral (also a fossil), Limestone, Chert/Flint (made of silica skeletons), Gypsum

Organic Rock example

Coal

Metamorphic Rocks