Author Question: What is metamorphic grade, and present an example of how a rock reaches its metamorphic grade? What ... (Read 69 times)

SGallaher96

  • Hero Member
  • *****
  • Posts: 509
What is metamorphic grade, and present an example of how a rock reaches its metamorphic grade? What will be an ideal response?

Question 2

What are index minerals, and what are they used for? Give an example of minerals that would be
  found in a low-grade, intermediate, and high-grade metamorphosed shale. What will be an ideal response?




djofnc

  • Sr. Member
  • ****
  • Posts: 318
Answer to Question 1

Metamorphic grade is a term that characterizes the degree to which a rock has undergone metamorphic
change. When shale is metamorphosed, chlorite first begins to crystallize at about 200C. If the
metamorphism stops there, the rock will be low grade. If temperatures and pressures increase, new
minerals replace chlorite, and if temperatures exceed 500C, sillimanite will appear.



Answer to Question 2

Index minerals are minerals that are known to form only within specific temperature and pressure
ranges. Their presence allows geologists to establish the metamorphic grade of a rock because the
highest-grade mineral indicates the temperature and pressure the rock was at for some time. Low-grade
minerals include chlorite, muscovite, and biotite; intermediate include muscovite, biotite, garnet,
staurolite, and kyanite; and sillimanite indicates high grade




Related Topics

Need homework help now?

Ask unlimited questions for free

Ask a Question
 

Did you know?

Malaria mortality rates are falling. Increased malaria prevention and control measures have greatly improved these rates. Since 2000, malaria mortality rates have fallen globally by 60% among all age groups, and by 65% among children under age 5.

Did you know?

Symptoms of kidney problems include a loss of appetite, back pain (which may be sudden and intense), chills, abdominal pain, fluid retention, nausea, the urge to urinate, vomiting, and fever.

Did you know?

About 60% of newborn infants in the United States are jaundiced; that is, they look yellow. Kernicterus is a form of brain damage caused by excessive jaundice. When babies begin to be affected by excessive jaundice and begin to have brain damage, they become excessively lethargic.

Did you know?

The human body's pharmacokinetics are quite varied. Our hair holds onto drugs longer than our urine, blood, or saliva. For example, alcohol can be detected in the hair for up to 90 days after it was consumed. The same is true for marijuana, cocaine, ecstasy, heroin, methamphetamine, and nicotine.

Did you know?

Certain topical medications such as clotrimazole and betamethasone are not approved for use in children younger than 12 years of age. They must be used very cautiously, as directed by a doctor, to treat any child. Children have a much greater response to topical steroid medications.

For a complete list of videos, visit our video library