Question

Zoom in and look at Sample F in detail. This igneous rock contains at least 50% of a dark greenish grey mineral that has been identified as calcium rich plagioclase. There is also about an equal amount of a dark greenish black mineral that forms a texture of interlocking crystals with the plagioclase. Thinking of Bowen's Reaction Series, the dark greenish black mineral would most likely be _________________________.
a. pyroxene (augite)
b. amphibole (hornblende)
c. biotite
d. muscovite

Answer 1

Answer:

a. pyroxene (augite)

Explanation:

Pyroxene is a mineral which is found in igneous and metamorphic rocks of the earth crust. They are dark green in color. their formation needs high degree of temperature and high pressure. Pyroxene is made up of silicon as a major element but some elements also present in it such as Ca, Na, Mg, Fe, Al and Ti. Its chemical formula is (Ca,Na)(Mg,Fe,Al,Ti)(Si,Al)2O6.