Definition
Chalk is a soft, white, powdery limestone consisting mainly of fossil shells of foraminifers
Very fine grained fault rock which is composed of glassy matrix that often contains inclusions of wall-rock fragments.
Discoverer
Unknown
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 pseudo- + tachylite, a glassy rock generated by frictional heat within faults.
Class
Sedimentary Rocks
Metamorphic Rocks
Sub-Class
Durable Rock, Soft Rock
Durable Rock, Hard Rock
Other Categories
Fine Grained Rock, Opaque Rock
Fine Grained Rock, Opaque Rock
Texture
Clastic or Non-Clastic
Quench
Color
Grey, White, Yellow
Black, Brown, Green, Grey, Pink, White
Durability
Durable
Durable
Appearance
Soft
Dull and Soft
Interior Uses
Decorative Aggregates, Homes, Interior Decoration
Decorative Aggregates, Entryways, Interior Decoration
Exterior Uses
As Building Stone, As Facing Stone, Paving Stone, Garden Decoration
As Building Stone, As Facing Stone, Garden Decoration
Other Architectural Uses
Powder
Curbing
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
As Dimension Stone, Cement Manufacture, for Road Aggregate, Making natural cement
Antiquity Uses
Artifacts, Monuments, Sculpture, Small Figurines
Artifacts, Monuments
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
Types
Chalk Marl and Marl
Cataclastic rock
Features
Clasts are smooth to touch, Is one of the oldest rock, Smooth to touch, Very fine grained rock
Host Rock for Lead
Archaeological Significance
Formation
Chalk is formed from lime mud, which accumulates on the sea floor which is then transformed into rock by geological processes.
Due to change in environmental conditions, rocks are heated and pressurized deep inside the Earth's surface. Pseudotachylite is formed from the extreme heat caused by magma or by the intense collisions and friction of tectonic plates.
Mineral Content
Calcite, Clay, Clay Minerals, Quartz, Sand
Iron Oxides, Pyroxene, Quartz, Stishovite, Sulfides
Compound Content
Ca, NaCl, CaO
Carbon Dioxide, Silicon Dioxide, Sulfur Dioxide, Sulphur
Types of Metamorphism
-
Burial Metamorphism, Cataclastic Metamorphism, Contact Metamorphism
Types of Weathering
Biological Weathering, Chemical Weathering
-
Types of Erosion
Chemical Erosion, Coastal Erosion, Water Erosion
-
Grain Size
Very fine-grained
Very fine-grained
Streak
White
Light to dark brown
Porosity
Highly Porous
Less Porous
Specific Gravity
2.3-2.4
2.46-2.86
Transparency
Opaque
Transparent to Translucent
Density
2.49-2.50 g/cm3
2.7-2.9 g/cm3
Resistance
Heat Resistant
Heat Resistant
Deposits in Eastern Continents
Asia
Brunei, India, Indonesia, Malaysia, Singapore, Thailand, Vietnam
South Korea
Africa
Cameroon, Chad, Ghana, Kenya, Malawi, Sudan, Tanzania, Togo, Zambia, Zimbabwe
Western Africa
Europe
England, France, Germany, Spain, United Kingdom
Great Britain, Switzerland
Deposits in Western Continents
North America
Canada, USA
-
Deposits in Oceania Continent
Australia
Adelaide, New Zealand, Queensland, Victoria, Yorke Peninsula
Central Australia, Western Australia
All about Chalk and Pseudotachylite Properties
Know all about Chalk and Pseudotachylite properties here. All properties of rocks are important as they define the type of rock and its application. Chalk belongs to Sedimentary Rocks while Pseudotachylite belongs to Metamorphic Rocks.Texture of Chalk is Clastic or Non-Clastic whereas that of Pseudotachylite is Quench. Chalk appears Soft and Pseudotachylite appears Dull and Soft. The luster of Chalk is dull while that of Pseudotachylite is vitreous. Chalk is available in grey, white, yellow colors whereas Pseudotachylite is available in black, brown, green, grey, pink, 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 Pseudotachylite are creating artwork, gemstone.