Page 103 - Atlas of Sedimentary Rocks Under The Microscope

Appendix 3

Preparation of a stained
acetate peel of a l i mestone

The f o llowing procedure ha� been f o und to work well with most using 500 ml or solution will depend on their surface areas.
lithified limestones of low porosity and has been used to make most of Using samples averaging about 5 em square, I 0-15 samples
the peels shown in this book. Porous limestones should first be can be accommodated. although it will be necessary to increase
impregnated with resin, otherwise evaporation of the acetone will the time in the solution as the acid becomes weaker. After
draw up W<ttcr onto the stained surface after step 6 (below). I 0-15 samples, the solution must either be discarded or
strengthened with a 2 3 ml of concentrated hydrochloric acid.
1 . Prepare a slab of rock, grinding f1at the surface to be peeled . The
s
final grinding should be made using 3F grade carborundum (c) All chemicals should he handled with great care. It i
recommended that protective gloves are worn throughout tire
powder. making of peels. Take care nor to inhale the acetone f u mes.
2. Prepare sta111 solutions A and B i n the concentrations described in
Appendix 2.
3. Mix solutions in the proportion A: B. 3:2. and pour into a shallow
container large enough to allow the whole oft he ground surface to
be in contact with the solution.
4. After ensuring that the surface to be peeled is free from dirt or
grease, immerse the rock slab in the stain solution so that the
surface to be peeled is completely covered by solution. This is done
best by holding the specimen with the ground surface downwards,
either by hand or in a clamp and retort stand. otherwise the
solution will be wasted on the unprepared surfaces. The specimen
should he immersed in the solution for 90 seconds. Agitate the
solution occasionally to remove gas bubbles from the undersur­
face of the slab.
5. Rinse the stained surface with water and leave for a few minutes
for excess water to evaporate.
6. Flood the surface with acetone allowing it to run oiT, taking the
excess stain with it.
7. Cut out a piece of thin acetate sheet (0.003 inch thickness is
suitable) slightly larger than the sample.
8. Arrange the rock sample with its stained surface uppermost and
hori70ntal. taking care not to tOuch the surface.
9. Flood the surface with acetone.
10. Lower the acetate sheet onto the �urfacc gently. taking care to
expel any air bubbles which may have fo rmed. No pressure is
required.
1 1 . Leave the slab and peel for half an hour at least. to allow the peel to
harden.
1 2 . Gcntl) peel the acetate sheet from the sample.
1 : 1. Trim and mount immediately between two pieces of glass to keep
the peel flat. ormal glass slides for thin sections arc suitable for
small samples.
The peel is now ready for examination under the microscope.
ole: (a) To makl: another peel of the same sample it is necessary 10
re-grind the surface \\ ith only the finest grit before repeating
steps 4 1 3 above.
(b) The number of samples which can he peeled successfully

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