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BRECCIA
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Breccia is a sedimentary rock which has usually undergone little chemical alteration. It is composed of a mixture of sedimentary, metamorphic and igneous rocks and has no essential minerals. It's composition depends on that of the preexisting rocks from which it has formed, therefore it is very variable in colour (often brown). It tends to contain random angular particles of various sizes which may be bonded together by a fine grained cement. Breccia can be distinguished from conglomerates because these are made up of rounded particles
It's name is derived from the German word Brecha, which means fragment. If breccia contains fragments of the same rock type then it is called monogenic. If it contains lots of different rock types then it is said to be polygenic.
It is very widespread and may be found in screes (piles of rock which have fallen to the cliff bottom). It may be found in Canada, Bristol (England), Scotland and Pennsylvania, USA.
Chrome Diopside is a pyroxene silicate of magnesium and calcium and therefore a member of the silicate group. It is a bright green form of diopside and derives it's colour from the presence of chromium. Diopside may be classed as chrome diopside if it contains enough chromium oxide to turn it green (greater than 1% by weight). Some specimens contain small amounts of chromium oxide (Cr2O3) in the form of an impurity (not as part of their chemical make up).
It has medium hardness (5.5-6.5 on the mohs scale) and may resemble emerald, although chrome diopside is found in a different rock formation. It forms mainly in metamorphic rocks in association with chromium bearing minerals.
The most well know source is Austria. It may also be found in Brazil, Canada, Finland, India, Italy, Russia, South Africa and Sri Lanka.
