Question

Describe the formation, characteristics, and minerals present of the following rocks:

Answer 1

Explanation:

Serpentine

• Formation: it forms through serpentinization, a geological low-temperature metamorphic process where low-silica mafic and ultramafic rocks are oxidized and hydrolyzed with water into serpentinite.
• Characteristics: rich in magnesium and water, light to dark green, greasy-looking and slippery feeling. It can resist the transfer of heat. A source of asbestos, architectural stone, ornamental stone, gem material
• Minerals present: it follows the formula (X)2-3(Y)2O5(OH)4 where X  can be magnesium, iron, nickel, aluminum, zinc, or manganese; and, Y will be silicon, aluminum, or iron.

Green Schist

• Formation: they form by regional metamorphism of mafic igneous rocks through depth of burial, and proximity to batholiths.
• Characteristics: The green is due to abundant green chlorite
• Minerals present: actinolite and epidote mainly, but they can also include quartz, orthoclase, talc, carbonate minerals, and amphibole.

Basalt Pillow

• Formation: it forms when lava of basaltic compositions erupted underwater. The rapid cooling of the lava forms the pillow-shaped bodies.
• Characteristics: they are volcanic igneous rocks, very dark, almost black color.
• Minerals present: Basalt has a lower percentage of silica and a higher percentage of iron and magnesium than other volcanic rocks.

Umber

• Formation: it develops in Cyprus massive sulfide deposits.
• Characteristics: is not one precise color, but a range of different colors, from medium to dark, from yellowish to reddish to grayish depending on the iron oxide and manganese in the clay
• Minerals present: contains iron oxide and manganese oxide and sulfide precipitates like pyrite.

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