15.07.2013 Views

Copyright by Nysha Chaderton 2009 - The University of Texas at ...

Copyright by Nysha Chaderton 2009 - The University of Texas at ...

Copyright by Nysha Chaderton 2009 - The University of Texas at ...

SHOW MORE
SHOW LESS

Create successful ePaper yourself

Turn your PDF publications into a flip-book with our unique Google optimized e-Paper software.

Argillaceous Rock Fragments<br />

Argillaceous rock fragments appear brown in color in plane polarized light. <strong>The</strong>y<br />

are generally deformed and in some cases transformed into pseudom<strong>at</strong>rix.<br />

Chert<br />

Chert is microcrystalline quartz. Like the other types <strong>of</strong> quartz, it is transparent in<br />

plane polarized light but exhibits a salt and pepper appearance in cross polarized light.<br />

Accessory Minerals<br />

Several accessory minerals occur in minor amount and are identified <strong>by</strong> the<br />

criteria listed below. <strong>The</strong>se include:<br />

polarized light.<br />

Biotite - identified <strong>by</strong> the distinctive brown to dark brown pleochroism in plane<br />

White mica - probably muscovite, exhibits second-order bi-refringence colors in<br />

cross-polarized light and is white to transparent in plane polarized light. Grains are thin,<br />

pl<strong>at</strong>y and elong<strong>at</strong>e. <strong>The</strong>y are <strong>of</strong>ten deformed and are more abundant in finer-grained<br />

samples.<br />

pleochroism.<br />

Chlorite - is present as rare chlorite grains with distinctive green-darker green<br />

Glauconite - is rare, but is distinctive with its green color in plane and cross<br />

polarized light and its rounded grain shape.<br />

31

Hooray! Your file is uploaded and ready to be published.

Saved successfully!

Ooh no, something went wrong!