The Naked Scientists

The Naked Scientists Forum

Author Topic: Identifying cleavage  (Read 2621 times)

Offline endgamex

  • First timers
  • *
  • Posts: 5
    • View Profile
Identifying cleavage
« on: 21/11/2010 16:13:38 »
I'm very confused about identifying cleavage, I know for instance that plagioclase has two good cleavages and quartz has none.  But when you have a very small amount of these minerals in a rock how can you see cleavage?  If I broke little tiny bits of plagioclase of a rock would they really be little rectangle shapes?  Wouldn't they be little angular shards just like quartz?  Quartz and plagioclase can both be white so you can't rely on colour, they both have similar hardness and lustre so with out a thin section I don't understand how you can tell the difference?  Can anyone help?   


 

Offline Bass

  • Neilep Level Member
  • ******
  • Posts: 1340
  • Thanked: 5 times
    • View Profile
Identifying cleavage
« Reply #1 on: 22/11/2010 01:53:12 »
First off, get a good hand lens.  Under hand lens, cleavage in feldspar produces a uniform, flat shiny surface (or 2 surfaces if the mineral is large enough).  Quartz can also be shiny, but only on crystal surfaces.  Quartz's conchoidal fracture doesn't produce a flat surface. 
 

Offline peppercorn

  • Neilep Level Member
  • ******
  • Posts: 1466
    • View Profile
    • solar
Identifying cleavage
« Reply #2 on: 22/11/2010 11:10:31 »
My, my - how mature we all must be to resist the obvious pun! ;D
 

The Naked Scientists Forum

Identifying cleavage
« Reply #2 on: 22/11/2010 11:10:31 »

 

SMF 2.0.10 | SMF © 2015, Simple Machines
SMFAds for Free Forums