Riya Loach posted an Question
August 30, 2020 • 20:40 pm 30 points
  • IIT JAM
  • Geology (GG)

5.which of the following 2 points minerals is unstable under high stress condition oa kyanite o b staurtolite ocsillimanite o d chlorite

5.Which of the following 2 points minerals is unstable under high stress condition OA Kyanite O B Staurtolite OcSillimanite O D Chlorite

1 Answer(s) Answer Now
  • 0 Likes
  • 4 Comments
  • 0 Shares
  • comment-profile-img>
    Rahul kumar

    Concept of stress and anti-stress minerals don't signify their stability field. An anti-stress mineal can also remain in high Pressure condition. Anti stress mineral is a term suggested for minerals such as cordierite, the feldspars, the pyroxenes, forsterite, and andalusite, whose formation in metamorphosed rocks is believed to be favored by conditions that are not controlled by shearing stress, but by thermal action and by hydrostatic pressure that is probably no more than moderate.

  • comment-profile-img>
    Rahul kumar best-answer

    In diagram, vertical axis represents pressure and Horizontal axis represents temperature. You can note the stability zone of different polymorphs of aluminosilicates. By looking at the diagram, you can observe following points; 1. Andalusite is stable under low Pressure & low temperature condition 2. Kyanite is stable under high pressure low temperature condition 3. Sillimanite is stable under high pressure high temperature condition Among all three polymorphs of Al2SiO5 only Kyanite and sillimanite can remain stable in high pressure condition

  • comment-profile-img>
    Rahul kumar

    Ans(B) Staurolite Staurolite can not be stable under very high pressure condition. Other minerals Kyanite, Staurolite and Chlorite can occur in high Pressure condition. Aluminosilicates stability diagram is attached for your reference, you can see that Kyanite and sillimanite can be stable under very high pressure. Chlorite can also occur in blueschist facies (high P facies) of pelitic rocks.

    cropped6220603783732988584.jpg
    eduncle-logo-app

    sir sillimanite is the anti stress mineral so, I think the correct opt will be sillimanite.. but other 3 are stress minerals

  • comment-profile-img>
    Sajan sarthak

    sillimanite is the mineral unstable in high pressure or stress condition. why you can see from the attached file of pressure temperature. sillimanite phase is nowhere at high pressure region.

    cropped2010035753748241793.jpg
whatsapp-btn

Do You Want Better RANK in Your Exam?

Start Your Preparations with Eduncle’s FREE Study Material

  • Updated Syllabus, Paper Pattern & Full Exam Details
  • Sample Theory of Most Important Topic
  • Model Test Paper with Detailed Solutions
  • Last 5 Years Question Papers & Answers