Definition
Chalk is a soft, white, powdery limestone consisting mainly of fossil shells of foraminifers
Variolites are a group of dark green basic igneous rocks which exhibit pale colored spots, or spherules, especially on weathered surfaces, that give them a pockmarked appearance
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 Latin varius, speckled, variegated
Class
Sedimentary Rocks
Igneous Rocks
Sub-Class
Durable Rock, Soft Rock
Durable Rock, Hard Rock
Other Categories
Fine Grained Rock, Opaque Rock
Opaque Rock
Texture
Clastic or Non-Clastic
Glassy, Massive, Porphyritic, Scoriaceous, Vesicular
Color
Grey, White, Yellow
Black, Brown, Light to Dark Grey
Durability
Durable
Durable
Appearance
Soft
Dull and Soft
Interior Uses
Decorative Aggregates, Homes, Interior Decoration
Floor Tiles, Flooring, Homes, Hotels, Kitchens
Exterior Uses
As Building Stone, As Facing Stone, Paving Stone, Garden Decoration
Garden Decoration, Office Buildings
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, Cobblestones, Rail Track Ballast, Roadstone
Antiquity Uses
Artifacts, Monuments, Sculpture, Small Figurines
Artifacts, Monuments, Sculpture
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
Cemetery Markers, Creating Artwork
Types
Chalk Marl and Marl
Metamorphic rock
Features
Clasts are smooth to touch, Is one of the oldest rock, Smooth to touch, Very fine grained rock
Has High structural resistance against erosion and climate, Very fine grained rock
Archaeological Significance
Formation
Chalk is formed from lime mud, which accumulates on the sea floor which is then transformed into rock by geological processes.
Variolites are a group of dark green basic igneous rocks that exhibit pale colored spots on weathered surfaces that give them a pockmarked appearance.
Mineral Content
Calcite, Clay, Clay Minerals, Quartz, Sand
Olivine, Plagioclase, Pyroxene
Compound Content
Ca, NaCl, CaO
Aluminium Oxide, CaO, Iron(III) Oxide, FeO, Potassium Oxide, MgO, MnO, Sodium Oxide, Phosphorus Pentoxide, Silicon Dioxide, Titanium Dioxide
Types of Metamorphism
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Burial Metamorphism, Cataclastic Metamorphism, Contact Metamorphism, Hydrothermal Metamorphism, Impact Metamorphism, Regional Metamorphism
Types of Weathering
Biological Weathering, Chemical Weathering
Biological Weathering, Chemical Weathering, Mechanical Weathering
Types of Erosion
Chemical Erosion, Coastal Erosion, Water Erosion
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Grain Size
Very fine-grained
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Streak
White
White to Grey
Porosity
Highly Porous
Less Porous
Specific Gravity
2.3-2.4
2.8-3
Transparency
Opaque
Opaque
Density
2.49-2.50 g/cm3
2.9-3.1 g/cm3
Resistance
Heat Resistant
Heat Resistant, Pressure Resistant, Wear Resistant
Deposits in Eastern Continents
Asia
Brunei, India, Indonesia, Malaysia, Singapore, Thailand, Vietnam
India, Russia
Africa
Cameroon, Chad, Ghana, Kenya, Malawi, Sudan, Tanzania, Togo, Zambia, Zimbabwe
South Africa
Europe
England, France, Germany, Spain, United Kingdom
Iceland
Deposits in Western Continents
North America
Canada, USA
Canada, USA
South America
Colombia
Brazil
Deposits in Oceania Continent
Australia
Adelaide, New Zealand, Queensland, Victoria, Yorke Peninsula
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All about Chalk and Variolite Properties
Know all about Chalk and Variolite properties here. All properties of rocks are important as they define the type of rock and its application. Chalk belongs to Sedimentary Rocks while Variolite belongs to Igneous Rocks.Texture of Chalk is Clastic or Non-Clastic whereas that of Variolite is Glassy, Massive, Porphyritic, Scoriaceous, Vesicular. Chalk appears Soft and Variolite appears Dull and Soft. The luster of Chalk is dull while that of Variolite is . Chalk is available in grey, white, yellow colors whereas Variolite is available in black, brown, light to dark grey 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 Variolite are cemetery markers, creating artwork.