Ageologist finds a layer of rock that is made of coarse-grained foliated particles arranged into bands and splits into sheets when struck with a hammer.

what type of rock did the geologist find?

a.
marble

b.
gneiss

c.
quartzite

d.
slate

Option (B)

Explanation:

Gneiss is a metamorphic rock which forms due to the extremely high pressure and temperature condition. It is characterized by the coarse and medium-sized grains and there is the presence of alternating dark and light-colored bands on it. The light color band contains felsic minerals such as feldspar, quartz and the dark band contains mafic minerals such as biotite, hornblende, garnet. It is a very high-grade metamorphic rock. These characteristics helps in identifying a gneissic rock.

Thus, the geologist found a gneissic rock.

Hence, the correct answer is option (B).