CHAPTER 4: STONES
º Stones are derived from rocks which form the earth s crust and
have no definite shape or chemical composition but are mixtures
of two or more minerals.
º Following are some important uses of stones in construction:
o Construction of residential and public buildings.
o Construction of dam, harbours, abutments for bridges.
o Facework of structures and forms of veneers for
decorative front and interior of building.
o As aggregate in concrete.
Classification of Rocks
º Can be classified according to geological, physical, chemical.
º Under geological classification, the rocks are classified into 3
o Igneous rocks
o Sedimentary rocks
o Metamorphic rocks
o Formed by cooling the molten lava or magma (during volcanic
eruption and earth s plate movement).
o The portion of lava, which comes outside the surface cools
quickly and forms the rock of non-crystalline nature called
o The rest of the portion that remains inside the earth undergoes
cooling at a slow rate and results in the formation of rock
crystalline variety known as granite.
o Formed by gradual deposition of disintegrated rocks (due to the
atmospheric actions), vegetable matter and clay at the bottom of
the rivers, lakes or sea.
o Are also called stratified because are formed in layers.
o Limestone and sandstone are in this category.
o Formed when sedimentary rocks or igneous rocks are subjected
to great heat and pressure inside the earth.
o This change of structure is called metamorphism.
o Example, limestone changes to marble, slate changes to gneiss.
Characteristics of Good Building Stones
o Appearance & colour have uniform and appealing colour, free
from flaw and clay holes. Have the ability to receive good
o Weight- should be high as heavier stones can resist greater force
and more compact and less porosity.
o Fineness of grain suitable for moulding works and less likely
o Resistant to fire- should have homogeneous composition and
free from calcium carbonate or iron oxide.
o Electrical resistant must be non-absorbent like slate.
o Hardness and toughness must be adequately hard and tough to
resist wear and tear.
o Strength have sufficient strength to be subjected to
o Durability compact and homogeneous stones are more
o Cost- depends on availability, ease of quarried out and method
of dressing (shaping the stone).
COMMON BUILDING STONES, THEIR COMPOSITION,
PROPERTIES AND USES
o It is igneous rock
o Composed of quartz (hard and least affected by CO2 and H2O),
feldspar (crystalline) and mica(dark, grey, black and brown in
o Water absorption is less than 1%
o Significantly strong and durable
o Finely grained granite takes a fine polish
o Compressive strength from 110 to 140 MN/m2
o It has least fire resistance as it cracks under a strong fire
o Its colour depends upon that of feldspar
o Fine grained granite is suitable for decorative purposes
o Most suitable for the construction of sea walls, bridge
o Large pieces are used as building blocks, the smaller as
railway ballast and the chippings for the manufacture of
concrete (aggregate) or artificial stone.
o It is a sedimentary rock
o It contains sand or quartz cemented by lime, mica, magnesium,
aluminium, iron oxide
o Shows sandy grains
o Usual colours are white, grey, brown, pink
o Compressive strength from 35 to 40 MN/m2
o Fine grained stones are strong and durable
o The sandstone of thin-bedded variety is called flagstone. It
splits easily into large slabs
o The fine grained and compact variety is suitable for
mouldings and carvings
o The rough and course grained stone is used for rubble
work (stone wall).
o It is a metamorphic rock due to the action of pressure to clay
o Composed of alumina mixed with sand or carbonate of lime
o Hard, tough and fine grained
o Grey or dark blue colour
o Can be cut into thin sheets
o Compressive strength from 60 to 70 MN/m2
o Produces a sharp metallic ring when struck with a light
o As floor and wall finishes, sanitary fittings
o As roof covering
Calgary Sandstone Ashler Saw Cut
TILED IN BLACK SLATE
LIMESTONE SLAB FOR WALLS
Stone is a natural solid formation of one or many minerals. There are thousands of
types of stone that have been quarried through the centuries. Quarries are located all
around the world. A majority of natural stone comes from Italy, Spain, Turkey, United
States, Mexico, China, Taiwan, India, Greece, Canada, France, and Brazil.
The minerals in stone came from the same liquid and gas minerals that formed the
earth. The Earth developed as a massive body of gas and liquid minerals that slowly
cooled and condensed to a solid core. Through pressure, the Earth's crust began to
form and heavy minerals were forced down to the core of the Earth where they were
trapped. As the crust got thicker, it squeezed around the inner core which created
intense pressure and heat from within the Earth. Crystals and other solid forms began
to grow from the mineral vapors that were being released. As the Earth's crust began
to expand and erode, heat and pressure pushed the solid minerals up to the Earth's
surface which formed colossal rock beds. It took up to one-hundred million years to
form some of these beds. Many of the beds are now used as quarries where the stone
Most of these minerals can be identified by their color, hardness, and crystal
formation. Crystals come in a variety of shapes and sizes. The wide array of these
minerals are often difficult to identify. Many stones look very similar to each other;
however, they are all very different.
TYPES OF STONE
The familiar stone types that are used today are identified through four categories:
sedimentary, metamorphic, igneous stone, and man-made.
I. Sedimentary rocks came from organic elements such as glaciers, rivers, wind,
oceans, and plants. Tiny sedimentary pieces broke off from these elements and
accumulated to form rock beds. They were bonded through millions of years of heat
Limestone: Mainly consists of calcite. It does not show much graining or crystalline
structure. It has a smooth granular surface. Varies in hardness. Some dense
limestones can be polished. Common colors are black, grey, white, yellow or brown. It
is more likely to stain than marble. Limestone is known to contain lime from sea water.
Sandstone: Is a very durable formation of quartz grains (sand). Usually formed in
light brown or red colors. Categorized by the most popular sandstone bonding agents
such as silica, calcium, clay, and iron oxide.
Soapstone: A very soft stone made of a variety of talc. It is a dense mineral that
wears well and is often resistant to stains.
Fossilstone: Considered a limestone that contains natural fossils such as sea shells
Travertine: Usually a cream or reddish color. It is formed through the accumulation of
calcite from hot springs. It contains lots of holes that were formed from water flowing
through the stone. These holes are often filled with synthetic resins or cements.
Requires lots of maintenance if the holes are not filled. Classified as a limestone and a
II. Metamorphic Rocks: Stone originates from a natural change from one type of
stone to another type through the mixture of heat, pressure, and minerals. The change
may be a development of a crystalline formation, a texture change, or a color change.
Marble: A recrystallized limestone that formed when the limestone softened from heat
and pressure and recrystallized into marble where mineral changes occurred. The main
consistency is calcium and dolomite. Ranges in many colors and is usually heavily
veined and shows lots of grains. Hardness rates from 2.5 to 5 on the MOH Scale.
Marble is classified into three categories:
1. Dolomite: If it has more than 40% magnesium carbonate.
2. Magnesium: If it has between 5% and 40% magnesium carbonate.
3. Calcite: If it has less than 5% magnesium carbonate.
Slate: A fine grained metamorphic stone that formed from clay, sedimentary rock
shale, and sometimes quartz. Very thin and can break easily. Usually black, grey, or
Serpentine: Identified by its marks which look like the skin of a serpent. Most popular
colors are green and brown. Hardness rates from 2.5 to 4 on the MOH Scale. Contains
serpentine minerals has lots of magnesium, and has an igneous origin. Does not
always react well to recrystallization or diamond polishing.
III. Igneous rocks are mainly formed through volcanic material such as magma.
Underneath the Earths surface, liquid magma cooled and solidified. Mineral gases and
liquids penetrated into the stone and created new crystalline formations with various
Granite: Primarily made of Quartz (35%), Feldspar (45%) and Potassium. Usually has
darker colors. Contains very little calcite, if any. Provides a heavy crystalline and
granular appearance with mineral grains. It is very hard material and easier to
maintain than marble. Yet, it is still porous and will stain. There are different types of
granite depending on the percentage mix of quartz, mica and feldspar. Black granite is
known as an Anorthosite. It contains very little quartz and feldspar and has a different
composition than true granite.
IV. Man Made Stones are derived of unnatural mixtures such resin or cement with
the additive of stone chips.
Terrazzo: Marble and granite chips embedded in a cement composition.
Agglomerate or Conglomerate: Marble chips embedded in a colored resin
Cultured or Faux Marble: A mix of resins that are painted or mixed with a paint to
look like marble.
Countries in the Top Place of Stone Production Ability:
The World Stone Organization reports that 70% of the world total stone production
distribute mostly in seven countries. China lies in the first place with annual
production ability of 11,000,000 tons, equal to 11% of the total world stone
production ability. Italy is only behind to China with 97,000,00 tons annually. Spain
is in the third place with annual production ability of 4,860,000,equal to 4.5% of the
world stone production. Immediately behind Spain is India, which can offer
4,750,000 tons amounting 4.4%. Portugal lies in the five places with annual
production ability of 4,350,000 tons, amounting 4.1%. Brazil and Korea are in the
sixth and seventh place in the world according to its stone production ability,
2,500,000 tons and 1,950,000 tons separately