Building Materials, Third Edition

‚™2—2ƒ SW

w
—™ ‚™ are formed from igneous or sedimentary rocks as a result of the action of
the earth movements, temperature changes, liquid pressures, etc. The resultant mass may have
a foliated structure, e.g. slate, gneiss, schist and phyallite or non-foliated structure, e.g. marble,
quartzite and serpentine. Examples of transformation of some of the rocks to metamorphic
rocks are given in Table 3.3.

„—˜    2QQ i'— 22„——22‚™!

ƒx y



—2™ w—

™2™

I8 q—

 q



P8 ƒ

 q



Q8 ƒ— —:



R8 v

 w—˜D2ƒ™



S8 w— w—˜

T8 ƒ— ƒ—D2™

D2&—



U8 w ƒ—

V8 h

 w—˜

W8 h

D2˜—— ƒ™



IH8 p

D2 Ī

D2—

II8 g— q

D2™



f—22€ ™—

2g——™  ™

The rocks may be classified as stratified, unstratified and foliated.

ƒ
—
 ‚™ show distinct layers along which the rocks can be split. The examples are
sandstone, limestone, shale, slate, marble, etc.

…
—
 ‚™ do not show any stratification and cannot be easily split into thin layers.
The examples of such rocks are granite, basalt, trap, etc.

p —
 ‚™ have a tendency to split up only in a definite direction. Most of the metamorphic
rocks have a foliated structure, except for quartzite and marble which have granulose structure.

f—22g ™—

2g——™  ™

The rocks may be classified as argillaceous, silicious and calcarious.

e —™X The principal constituent is clay (Al 2 O 3 ). The rocks are hard and brittle, e.g. slate,
laterite, etc.

ƒ ™X The principal constituent is silica (SiO 2 ), i.e. sand. The rocks are very hard and
durable, e.g. granite, basalt, trap, quartzite, gneiss, syenite, etc.

g— ™—X The principal constituent is lime, e.g. limestone, marble, dolomite, etc.

QR …e‚‚‰sxq2yp2ƒ„yxiƒ

The only operation involved in the production of natural stone is the quarrying process. The
open part of the natural rock from which useful stone is obtained is known as quarry. While