« previous next »

Author Question: Obsidian is a felsic rock, yet has a black color. Explain. What will be an ideal ... (Read 23 times)

BrownTown3

  • Hero Member
  • *****
  • Posts: 564
on: Jul 16, 2018
Obsidian is a felsic rock, yet has a black color. Explain.
 
  What will be an ideal response?

Question 2

Define partial melting and explain how it affects the magma composition.
 
  What will be an ideal response?


ryrychapman11

  • Sr. Member
  • ****
  • Posts: 334
Reply #1 on: Jul 16, 2018
Answer to Question 1

The unexpectedly dark color of this felsic rock results from the presence of tiny crystals of black magnetite scattered throughout transparent glass. Thin slivers of obsidian are colorless, rather than black, which shows that even a low concentration of magnetite crystals strongly affects the color of thick samples.

Answer to Question 2

Partial melting occurs when a rock does not melt completely to form magma. Only some minerals in the rock completely melt, so the resulting magma does not have the same composition as the original rock. Partial melting typically creates magma that is relatively richer in silica than the original rock. For example, partial melting of an ultramafic rock (peridotite) forms a mafic (basaltic) magma; partial melting of a mafic rock (basalt) forms to intermediate or felsic magmas.


Related Topics

Need homework help now?

Ask unlimited questions for free

Ask a Question
« previous next »
 

Did you know?

Methicillin-resistant Staphylococcus aureus or MRSA was discovered in 1961 in the United Kingdom. It if often referred to as a superbug. MRSA infections cause more deaths in the United States every year than AIDS.

Methicilli ...
Did you know?

About 600,000 particles of skin are shed every hour by each human. If you live to age 70 years, you have shed 105 pounds of dead skin.

Did you know?

There are approximately 3 million unintended pregnancies in the United States each year.

Did you know?

Between 1999 and 2012, American adults with high total cholesterol decreased from 18.3% to 12.9%

Did you know?

Long-term mental and physical effects from substance abuse include: paranoia, psychosis, immune deficiencies, and organ damage.

Color enhanced X-ray showing a pacemaker implanted in the left side of the chest and the electrode w Color enhanced X-ray showing a pacemaker implanted in the left side of the chest and the electrode w
Clay Lohmann, Black Lung. Clay Lohmann, Black Lung.
Rashid Johnson, Souls of Black Folk. Rashid Johnson, Souls of Black Folk.
What are examples of ideal forms? What are examples of ideal forms?
Labeling of black cohosh Labeling of black cohosh
The study of how traits such as flower color are passed from generation to generation provided the m The study of how traits such as flower color are passed from generation to generation provided the m
Video: Double Stranded DNA Molecule Animation

For a complete list of videos, visit our video library