Page 102 - Atlas of Sedimentary Rocks Under The Microscope

Appendix 2

S t a i n i n g a t h i n section
of a limestone

The procedure detailed below, adapted from Dickson ( 1965), has been
found generally satisfactory and has been used in preparation of most
of the stained sections shown in this book. Two stains are required
AliLarin Red S and potassium f e rricyanide.
I. Prepare a thin section of the rocks as described n Appendix I but
i
omitting the coverslip. Ensure that no dirt or grease adheres to the
surface.
2. Prepare two staining solutions:
Solution A: Alizarin Red S concentration of 0.2 gj I 00 ml of
1.5% hydrochloric acid ( 1 5 ml pure acid made up to I litre with
water).
Solution 8: Potassium f e rricyanide concentration 2 g/ I 00 rnl of
1.5% hydrochloric acid.
3. Mix solutions A and Bin the proportion 3 parts by volume of A 10 2
parts of B.
4. Immerse the thin section in the mixture of solutions for 30-45
seconds, agitating gently for at least part of the time to remove gas
bubbles from the surface.
5. Wash the stained se c tion in running water for a few seconds.
6. Allow to dry.
7. Cover with polyurethane varnish or a coverslip in the normal way.
Note: The solution of Alizarin Red S in acid may be made up
beforehand and will keep. but the potassium lerricyanide must be
made fresh each time. A large number of sections can be stained with
250 rnl of stain solution.

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