Hong Kong Geology Guide Book Geotechnical Engineering Office ...

Appendix II
Table of characteristics of the common minerals found at Ma On Shan
Mineral Origin and Occurrence Hardness Colour
Actinolite Found within iron-bearing ore 5.5-6 Various shades of
deposits associated with contact
green. Darker green
metamorphism of carbonate rocks
with increasing iron
content
Amphibole The general name for a group of 5-6 Dark colours. Can be
(Group) minerals. An important
green, or brown to
rock-forming mineral
black
Andradite Product of contact metasomatism. 7 Commonly brown.
An important constituent of skarn
Also yellow, green or
deposits
black
Biotite Dark coloured, platey, rock- 2.5-3 Black or dark brown
(Mica) forming mineral in igneous rocks
Calcite Found in various geological 3 Colourless or white.
settings. The major constituent of
Impurities produce
carbonate rocks
other colours
Chalcedony Cryptocrystalline (no visible 7 Variety of colours.
crystals) mineral. Can form in a
Can be red, green,
low or high temperature
yellow, brown, black,
hydrothermal deposit
etc. Material used for
arts and crafts
Chlorite Common in metamorphic rocks or
hydrothermally altered rocks
2-2.5 Dark to light green
Diopside A common constituent of skarn. 5-6 Light green to light
Associated with metasomatism
greyish green
Epidote Common in contact
6.5 Green or yellowish
metamorphosed ore deposits. Late
stage metasomatic alteration
product of skarn minerals. Also
common in altered volcanic rocks
green
Feldspar The general name for a group of 7 Grey or greyish white
(Group) minerals. Feldspar is a widely
distributed rock-forming mineral,
important for rock classification
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