Chalk

Chert

Chalk and Chert

Chalk

Chert

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Definition

Chalk is a soft, white, powdery limestone consisting mainly of fossil shells of foraminifers

Chert is a hard, dark, opaque sedimentary rock which is composed of silica with an amorphous fine-grained texture

History

Origin

Discoverer

Unknown

Etymology

From old English cealc chalk, lime, plaster; pebble, from Greek khalix small pebble, in English transferred to the opaque, white, soft limestone

From flint-like quartz, 1670s, of unknown origin- a local term, which has been taken into geological use

Class

Sedimentary Rocks

Sub-Class

Durable Rock, Soft Rock

Durable Rock, Hard Rock

Family

Group

Other Categories

Fine Grained Rock, Opaque Rock

Texture

Clastic or Non-Clastic

Banded, Rough

Color

Grey, White, Yellow

Black, Brown, Green, Grey, Red, White

Maintenance

Less

Durability

Durable

Water Resistant

✔ ✘

Scratch Resistant

✔ ✘

Stain Resistant

✔ ✘

Wind Resistant

✔ ✘

Acid Resistant

✔ ✘

Appearance

Soft

Glassy or Pearly

Uses

Architecture

Interior Uses

Decorative Aggregates, Homes, Interior Decoration

Decorative Aggregates, Homes

Exterior Uses

As Building Stone, As Facing Stone, Paving Stone, Garden Decoration

As Building Stone, As Facing Stone, Garden Decoration, Office Buildings

Other Architectural Uses

Powder

Curbing

Industry

Construction Industry

As Dimension Stone, Cement Manufacture, Construction Aggregate, for Road Aggregate, Making natural cement, raw material for manufacture of quicklime and slaked lime, Source of calcium

Arrowheads, Construction Aggregate, Cutting Tool, Spear Points

Medical Industry

Antiquity Uses

Artifacts, Monuments, Sculpture, Small Figurines

Artifacts, Monuments

Other Uses

Commercial Uses

Alumina Refineries, Creating Artwork, Drawing on blackboards, Gymnasts, athletes and mountain climbers use for grip, In aquifers, Paper Industry, Production of Lime, Raw material for manufacture of quicklime, slaked lime, Soil Conditioner, Whiting, Whiting material in toothpaste, paint and paper

Creating Artwork, Gemstone, In fire-starting tools, Jewelry, To ignite fire, Used in flintlock firearms

Types

Chalk Marl and Marl

Flint, Jasper, Radiolarite, Common Chert, Chalcedony, Agate, Onyx, Opal, Magadi-type Chert, Porcelanite, Siliceous Sinter

Features

Clasts are smooth to touch, Is one of the oldest rock, Smooth to touch, Very fine grained rock

Clasts are smooth to touch, Easily splits into thin plates, Has High structural resistance against erosion and climate

Archaeological Significance

Monuments

Famous Monuments

Sculpture

Famous Sculptures

Pictographs

Petroglyphs

Figurines

Fossils

Present

Formation

Chalk is formed from lime mud, which accumulates on the sea floor which is then transformed into rock by geological processes.

Chert forms when microcrystals of silicon dioxide grow within soft sediments that become limestone or chalk. The chert formation can be either of chemical or biological origin.

Composition

Mineral Content

Calcite, Clay, Clay Minerals, Quartz, Sand

Quartz, Silicon

Compound Content

Ca, NaCl, CaO

Silicon Dioxide

Transformation

Metamorphism

✔ ✘

Types of Metamorphism

Weathering

✔ ✘

Types of Weathering

Biological Weathering, Chemical Weathering

Erosion

✔ ✘

Types of Erosion

Chemical Erosion, Coastal Erosion, Water Erosion

Chemical Erosion

Properties

Physical Properties

Hardness

16.5-7

1 7

👆🏻

Grain Size

Very fine-grained

Fracture

Uneven, Splintery or Conchoidal

Streak

White

Porosity

Highly Porous

Luster

Dull

Waxy and Dull

Compressive Strength

5.00 N/mm²450.00 N/mm²

0.15 450

👆🏻

Cleavage

Toughness

1.5

Specific Gravity

2.3-2.42.5-2.8

0 8.4

👆🏻

Transparency

Opaque

Translucent to Opaque

Density

2.49-2.50 g/cm³2.7 g/cm³

0 1400

👆🏻

Thermal Properties

Specific Heat Capacity

0.90 kJ/Kg K0.74 kJ/Kg K

0.14 3.2

👆🏻

Resistance

Heat Resistant

Heat Resistant, Impact Resistant, Pressure Resistant, Wear Resistant

Reserves

Deposits in Eastern Continents

Asia

Brunei, India, Indonesia, Malaysia, Singapore, Thailand, Vietnam

China, India, Iran, Japan, Oman, Russia, Saudi Arabia, Taiwan, Thailand, Vietnam

Africa

Cameroon, Chad, Ghana, Kenya, Malawi, Sudan, Tanzania, Togo, Zambia, Zimbabwe

Kenya, Morocco, South Africa, Tanzania

Europe

England, France, Germany, Spain, United Kingdom

Austria, France, Greece, Italy, Malta, Poland, Portugal, Serbia, Spain, Sweden, United Kingdom

Others

Greenland, Mid-Atlantic Ridge

Deposits in Western Continents

North America

Canada, USA

Canada, Mexico, USA

South America

Colombia

Bolivia, Brazil

Deposits in Oceania Continent

Australia

Adelaide, New Zealand, Queensland, Victoria, Yorke Peninsula

New South Wales, Queensland, South Australia, Western Australia

All about Chalk and Chert Properties

Know all about Chalk and Chert properties here. All properties of rocks are important as they define the type of rock and its application. Chalk and Chert belong to Sedimentary Rocks.Texture of Chalk is Clastic or Non-Clastic whereas that of Chert is Banded, Rough. Chalk appears Soft and Chert appears Glassy or Pearly. The luster of Chalk is dull while that of Chert is waxy and dull. Chalk is available in grey, white, yellow colors whereas Chert is available in black, brown, green, grey, red, white colors. The commercial uses of Chalk are alumina refineries, creating artwork, drawing on blackboards, gymnasts, athletes and mountain climbers use for grip, in aquifers, paper industry, production of lime, raw material for manufacture of quicklime, slaked lime, soil conditioner, whiting, whiting material in toothpaste, paint and paper and that of Chert are creating artwork, gemstone, in fire-starting tools, jewelry, to ignite fire, used in flintlock firearms.