Igneous Rock
- Igneous rock is formed when melted rock cools and hardens.
Created by lava from volcanoes or magma that cools inside the Earth.
Granite -
Granite is one of the most common rocks on Earth, and is the
most common igneous rock. This dense stone is used in construction,
for everything from basic building to beautiful polished
countertops.
Basalt
- Basalt is a dark coloured, fine-grained, igneous rock
composed mainly of plagioclase and pyroxene minerals. It most
commonly forms as an extrusive rock, such as a lava flow. Crushed
basalt is used for road base, concrete aggregate, asphalt pavement
aggregate, railroad ballast, filter stone in drain fields and may
other purposes.
Obsidian
- Most igneous rock forms below the Earth's surface, but one
rock-obsidian forms above the surface.This jet-black glass is actually
cooled lava. Obsidian
gathered from volcanic eruptions is used to make arrow heads,
weapons, household knives and more. Even today some surgical
instruments are made from obsidian-tipped tools.
Pumice
- Pumice stone is found near the site of a volcanic eruption
which sent rock and molten lava to the surface. This lightweight,
airy rock is often ground up and used as an abrasive in soaps and
household cleaners, as well as for industrial purposes.
Olivine
- Olivine is a very common silicate mineral that occurs
mostly in dark-coloured igneous rocks like peridotite and basalt. It
is usually easily identifiable because of its bright green colour and
glassy luster. Olivine is a mineral that is not often used in
industry. Most olivine is used in metallurgical processes as a slag
conditioner.
Syenite
- Syenites are formed due to alkaline igneous activities and
are generally formed in thick continental crustal areas. For the
formation of Syenite, it is necessary to melt granitic or igneous
protolith to low degree of partial melting.
Diorite
- Diorite is the name used for a group of coarse-grained
igneous rocks with a composition between that of granite and basalt.
In the stone industry, diorite is often cut into facing stone, tile,
ashlars, blocking, pavers, curbing and a variety of dimension stone
products. These are used as construction stone or polished and used
as architectural stone.
Graphite
- Graphite archaically referred to as plumbago, is a
crystalline form of carbon. Graphite is naturally found in Sri
Lanka, Canada and USA. It is also called Lead Black because it looks
like the metal lead. Graphite is used in batteries, steel making,
pencils etc.
Talc
– Talc is a clay mineral composed of hydrated magnesium
silicate. It occurs as foliated to fibrous masses. It is the softest
known mineral and listed as 1 on the Mohs hardness scale. Talc is
used in many industries - including paper making, plastic, paint and
coatings, rubber, food, electric cable, pharmaceuticals, cosmetics
and ceramics.
Sedimentary Rock
- Sedimentary rock is weathered into many pieces of rock and
soil which then settles into layers. The layers are squeezed
together until they harden into rock. Found in locations where
oceans, lakes or other bodies of water exist or once existed.
Shale
- Shale rocks are those that are made of clay-sized particles
and are have a laminated appearance. Shale is the abundant rock
found on Earth. Roughly 70% of the Earth's surface is covered by
shale. Shale that has a high content of natural gas has been
recently used as an energy source.
Conglomerate
- Conglomerate is a coarse-grained clastic sedimentary rock
that is composed of a substantial fraction of rounded to subangular
gravel-size clasts. Conglomerate has very few commercial uses. Its
inability to break cleanly makes it a poor candidate for dimension
stone.
Sandstone
- Sandstone is a type of rock that forms when grains of sand
are compacted together over significant periods of time. Sandstone
comes in a variety of colours including red, yellow, grey and brown.
Sandstone is popular in constructing buildings because it is
resistant to weathering.
Lime Stone
– Limestone is a sedimentary rock composed largely of the
minerals calcite and aragonite, which are different crystal forms of
calcium carbonate (CaCO3). Limestone is very common in architecture.
Many landmarks across the world, including the Great Pyramid are
made of limestone.
Coal
– Coal is a combustible black or brownish-black sedimentary
rock usually occurring in rock strata in layers or veins called coal
beds or coal seams. Coal is extracted from the ground by coal
mining. Coal is primarily used as a solid fuel to produce
electricity and heat through combustion. It is also used as a source
of heat for manufacturing processes.
Serpentinite
– Serpentinite is a rock composed of one or more serpentine
group minerals. Minerals in this group are formed
by serpentinisation, a hydration and metamorphic transformation of
ultramafic rock from the Earth's mantle. Serpentinite is used as a
decorative stone in architecture.
Lignite
- Lignite, often referred to as brown coal, is a soft brown
combustible sedimentary rock formed from naturally compressed peat.
It is considered the lowest rank of coal due to its relatively low
heat content. It has a carbon content around 60-70%. It is mined all
around the world and is used almost exclusively as a fuel for
steam-electric power generation.
Metamorphic Rock
- Metamorphic rock forms when igneous, sedimentary or other
metamorphic rock is changed by heat and pressure. This type of rock
is buried deep within the Earth where it is created from the heat
and pressure found there.
Slate
- Slate is a metamorphic rock that forms from mudstone or
shale. Slate is mostly made of clay but the clay can change to mica
under extreme degrees of pressure. Slate normally forms in basins
between convergent plate boundaries. Slate is used for different
varieties of flooring and roofing.
Marble
- Marble is a metamorphic rock that is formed when limestone
or dolomite is exposed to the right heat and pressure conditions.
Marble has a uniform texture when it forms and is sought after as a
building material for its strength, its beautiful striations and
colours and its sheen when polished.
Schist
- Schist is a metamorphic rock that contains flakes of mica.
Schist is often referred to as schistosity because of its large mica
flakes. Most schist rocks originate as some type of clay or mud.
Schist is often used as a guide to measure specific sizes and
dimensions of objects. Schist has been previously used to make
decorative rock walls.
Gneiss
- Gneiss is a type of metamorphic rock that forms when a
sedimentary or igneous rock is exposed to extreme temperatures and
pressure. Gneiss is so abundant on the lower level of the Earth's
crust that if you drill anywhere on the surface, you will eventually
strike gneiss. Gneiss has also been used to construct buildings and
gravestones.
Quartzite
- Quartzite is formed when grains of quartz sand melt
together under high heat and extreme pressure. While most quartzite
is white or grey, if the sand contained iron oxides, then the
quartzite formed can be a nice shade of soft pink or rose. The
resulting rock is very hard and very uniform in its texture.
Phyllite
– Phyllite is a type of foliated metamorphic rock created
from slate that is further metamorphosed so that very fine grained
white mica achieves a preferred orientation. It is primarily
composed of quartz, sericite mica and chlorite. Phyllites are
usually black to grey or light greenish grey in colour.
Ores
– An ore is a type of rock that contains sufficient
minerals with important elements including metals that can be
economically extracted from the rock. The ores are extracted from
the earth through mining, they are then refined to extract the
valuable element or elements.
Gold
- Gold is a transition metal and a group 11 element. It is one
of the least reactive chemical elements and is solid under standard
conditions. The metal therefore occurs often in free elemental form,
as nuggets or grains, in rocks, in veins and in alluvial deposits.
Consumption of gold produced is about 50% in jewellery, 40% in
investments and 10% in industry.
Silver
- A soft, white, lustrous transition metal. Silver occurs
naturally in its pure, free form, as an alloy with gold and other
metals and in minerals such as argentite and chlorargyrite. Most
silver is produced as a byproduct of copper, gold, lead and zinc
refining. Silver is used as jewellery, currency, silverware, water
purification, solar energy etc.
Hematite -
Hematite is the mineral form of iron oxide (Fe2O3), one of
several iron oxides. Hematite crystallizes in the rhombohedral
lattice system and it has the same crystal structure as ilmenite and
corundum. It is mined as the main ore of iron. Hematite is harder
than pure iron, but much more brittle.
Copper Ore
- Copper is an element and a mineral. It is found in the
oxidized zones of copper deposits in hydrothermal veins, in the
cavities of basalt and as pore fillings and replacements in
conglomerates. It is rarely found in large quantities. Most copper
produced is extracted from sulfide deposits. Most copper mined today
is used to conduct electricity - mostly as wiring.
Bauxite
- Bauxite, an aluminium ore, is the world's main source of
aluminium. Bauxite is a rock formed from a laterite soil that has
been severely leached of silica and other soluble materials in a wet
tropical or subtropical climate. Almost all of the aluminium that has
ever been produced has been extracted from bauxite.
Mercury
- Mercury occurs in deposits throughout the world mostly as
cinnabar. The red pigment vermilion is obtained by grinding natural
cinnabar or synthetic mercuric sulfide. Mercury is used in
thermometers, barometers, manometers, sphygmomanometers, float
valves, mercury switches, mercury relays, fluorescent lamps and
other devices.
Uraninite
- Uraninite, formerly pitchblende, is a radioactive,
uranium-rich mineral and ore. Uraninite is a major ore of uranium.
All uraninite minerals contain a small amount of radium as a
radioactive decay product of uranium.Small amounts of helium are
also present in uraninite as a result of alpha decay.
Crystals
- A solid figure that is made up of a repeating pattern of
geometric shapes is known as a crystal. Crystals form when a liquid
cools and hardens. There are four types of crystals: covalent,
metallic, molecular and ionic.
Corundum Crystal
– Corundum crystal is a crystalline form of aluminium oxide
typically containing traces of iron, titanium, vanadium and
chromium. It is a rock-forming mineral. It is one of the naturally
transparent materials, but can have different colours when
impurities are present. Corundum occurs as a mineral in mica schist,
gneiss and some marbles in metamorphic terranes.
Fluorite
– Fluorite is a mineral made up of calcium and fluoride or
calcium fluoride. It can come in every single colour on the colour
spectrum. Pure fluorite is colourless. When fluorite is coloured it is
because of various impurities. Fluorite glows when it is exposed to
UV light. Because of its soft texture, fluorite is used in carving.
Halite
- Halite is a mineral, commonly known as rock salt or salt.
It is made up of sodium and calcium. Halite is typically colourless
or white. It is one of the oldest used minerals. Halite is typically
found in underground salt beds. Halite is used as a seasoning for
food and is pleasant to the taste. Halite is essential for the human
body to function.
Sulphur -
Sulphur (S) is a bright yellow non-metallic element with an
atomic number of sixteen. Sulphur occurs naturally as an element but
can also be found in a number of compounds and minerals. Sulphur is
vital for living organisms.
Diamond -
Diamonds, one of the most coveted gems on earth, are a
different form of carbon. They are formed under intense pressure and
heat over billions of years. Carbon atoms are arranged in diamonds
in such a way that it makes the diamond the hardest natural material
known to man. Diamonds are the most popular gem for wedding
jewellery.
Opal
– Opal is a hydrated amorphous form of silica. Because of
its amorphous character, it is classed as a mineraloid, unlike
crystalline forms of silica, which are classed as minerals. It is
deposited at a relatively low temperature and may occur in the
fissures of almost any kind of rock, being most commonly found with
limonite, sandstone, rhyolite, marl and basalt.
Emerald
- Emeralds are a green-coloured gemstone, prized around the
world for their beauty and value. Most emeralds are found in areas
where large quartz deposits are also located. Emeralds are made of
beryl. This is also what makes the aquamarine gemstone, but emeralds
get their colour from small amounts of vanadium and chromium.
Ruby
– Ruby is a pink to blood-red coloured gemstone, a variety
of the mineral corundum. The red colour is caused mainly by the
presence of the element chromium. Ruby has a hardness of 9.0 on the
Mohs scale. The world's most expensive ruby is the Sunrise Ruby.
Topaz
– Topaz is a silicate mineral of aluminium and fluorine.
Pure topaz is colourless and transparent but is usually tinted by
impurities, typical topaz is wine red, yellow, pale grey,
reddish-orange, or blue brown. Topaz is commonly occurs with silicic
igneous rocks of the granite and rhyolite type.
Minerals
– A mineral is a naturally occurring substance,
re-presentable by a chemical formula, that is usually solid and
inorganic and has a crystal structure. There are over 5,300 known
mineral species.
Gemstone
– A gemstone is a piece of mineral crystal, which in cut
and polished form, is used to make jewellery or other adornments.
Rock Cycle
- The rock cycle is geological concept that explains the
changes over long periods of time that occur in igneous, metamorphic
and sedimentary rocks. Each of these kinds of rocks undergoes
changes or destruction when its environment is out of balance. This
kind of change in equilibrium can be caused by atmospheric changes,
plate tectonic activity, the movement of bodies of water and more.
The rock cycle also demonstrates how
three very different types of rock can be related to each other. It
shows how the processes involved in changing rocks differ with the
type of rock involved.
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