Geotechnical and Materials Engineering Standards for Bridge ...

Fine Grained lgneous
Coarse Grained Metamorphic LT 95
Hedium Grained He tamorphic LT 368
Fine Grained Metamorphic LT 189
... 111..*,. ..... 11.1.1
.* ,,....,*
.** I,., 1 1
ROCK HASS DESCRIPTION - This column is far a general descfption of
thi rock mass. The intact rock should be described according to its
colour, grain size, fabxic, texture and rock type, Grain size
refers to the average dimension of the mineral or rock fragments.
For sedimentary rocks the size ranges used for sofla are
appropriafe. Coarse graEned igneous and metamorphic rocks have a
grain, slze greater than 2 mm and fine grained igneous and
metamorphic rocks have grain sizes less than .O6 m.
The texture of a rock Is its general physical appearance including
the geometric aspects of the component particles or crystals. t.g.
sLze, shape and arrangement of the sedimentary particles or the
crystalliniv or granularity of an igneous rock. Fabrfc refers
specifically to the arrangement of the grains, In sedimentary rocks,
ft is the orientation of discrete particles arid in crystallina rocks
for the pattern produced by the shapes and orientation of the