148 SILICATES
Banded jasper | The dramatic colour
banding in this example of jasper rough
clearly shows why it has been a popular
carving and gem material since antiquity.
Red jasper | This variety of red
jasper from Arizona, USA, shows
colour mottling that will make colourful
and interesting cabochons.
Chrysoprase | This gem chrysoprase
specimen displays a beautiful deep green
colour. Chrysoprase remains one of the most
sought-after varieties of chalcedony.
Water agate | Originating from a single locality
in Brazil, agates of this variety are actually hollow
geodes filled with preserved water, revealed by grinding
a “window” into the inside.
Heliotrope rough | This specimen consists
of heliotrope, a green variety of chalcedony
shot through with red patches of iron oxide,
for which it is also known as bloodstone.
Rough
Gem rough | This fine piece of massive gem
carnelian rough has good colour all the way
through, and excellent translucency. It is
naturally dyed with iron oxide.
Water-filled interior
Colour variations
Inclusion
Fractured edges
Colouring caused
by iron oxide
Cross-sectional
view of interior
Deep green colouring
Good
translucency
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