is pyroxene intrusive or extrusive?

Question

is pyroxene an intrusive igneous rock (formed underground) or an extrusive igneous rock (formed aboveground) ?

Answer 1

Pyroxene is not a rock. It is a mineral. it can be present in both intrusive (ex: gabbro) and extrusive (ex: basalt) rocks.

Answer 2

iggy,

Geomatic is quite right. Pyroxene is a mineral and not a rock, and it can be found both in extrusive and intrusive rocks. The crystal size will be different in these two cases, but the presence of pyroxene depends on the chemical evolution of the magma that crystallizes it and NOT on where it crystallized.

Answer 3

Within the rock, it will usually be very fine grained due to rapid cooling and therefore tends to be aphanitic (very fine grained) where crystals are very difficult to identify, even under light microscopy. SEM (scanning electron microsope) images are more useful at studying the mineralogy of aphanitic rocks. [Note: an extrusive igneous rock, also includes a type of rock known as Tuff. A tuff is an igno-sedimentary rock formed from tephra (ash fall). Bits of magma solidify whilst in the air as they are forcefully ejected from the volcano and can travel many km, depending upon the size of the eruption, size of the rock and height of the eruption column). As the 'bits' fall they form layers which mimic sedimentary layering and produces beds in lithified units. They can contain volcanic bombs (large air fall) and are usually very fine grained. Speaking from experience they are mistaken for sedimentary rocks, but are certainly igneous in origin. They are often associated with basic eruptions and often interbedded with igneous flows.] Intrusive rocks tend to be more coarsely grained and are much easier to work with than extrusive rocks. They too can contain inclusions which are termed 'xenoliths' and are fragments of the country rock which have fallen into the magma from the walls of the body.

Answer 4

pyroxene is a mineral which can be associated with other minerals to form rocks which are intrusive forming! they are formed under high pressure and temperature, because of there extreme depth they are found from extreme weathering of very old continental sheild rocks.