Definition
Websterite is ultramafic and ultrabasic rock that consists of roughly equal proportions of orthopyroxene and clinopyroxene. It is a special type of pyroxenite.
Chalk is a soft, white, powdery limestone consisting mainly of fossil shells of foraminifers
Origin
Webster, North Carolina
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Discoverer
Unknown
Unknown
Etymology
From the town of Webster located in North Carolina
From old English cealc chalk, lime, plaster; pebble, from Greek khalix small pebble, in English transferred to the opaque, white, soft limestone
Class
Igneous Rocks
Sedimentary Rocks
Sub-Class
Durable Rock, Hard Rock
Durable Rock, Soft Rock
Other Categories
Coarse Grained Rock, Opaque Rock
Fine Grained Rock, Opaque Rock
Texture
Clastic, Granular, Phaneritic, Porphyritic
Clastic or Non-Clastic
Color
Black to Grey, Bluish - Grey, Dark Greenish - Grey, Green, Light Greenish Grey
Grey, White, Yellow
Durability
Durable
Durable
Appearance
Layered, Banded, Veined and Shiny
Soft
Interior Uses
Countertops, Decorative Aggregates, Entryways, Floor Tiles, Flooring, Interior Decoration
Decorative Aggregates, Homes, Interior Decoration
Exterior Uses
As Building Stone, As Facing Stone, Garden Decoration, Paving Stone
As Building Stone, As Facing Stone, Paving Stone, Garden Decoration
Other Architectural Uses
Curbing
Powder
Construction Industry
As Dimension Stone, Building houses or walls, Cement Manufacture, Construction Aggregate, for Road Aggregate
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
Antiquity Uses
Artifacts
Artifacts, Monuments, Sculpture, Small Figurines
Commercial Uses
Cemetery Markers, Commemorative Tablets, Creating Artwork, Laboratory bench tops, Jewelry, Sea Defence, Tombstones
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
Types
Ultramafic rock
Chalk Marl and Marl
Features
Generally rough to touch, Is one of the oldest rock
Clasts are smooth to touch, Is one of the oldest rock, Smooth to touch, Very fine grained rock
Archaeological Significance
Formation
Websterite can be formed as cumulates in ultramafic intrusions by accumulation of pyroxene crystals at the base of the lava chamber.
Chalk is formed from lime mud, which accumulates on the sea floor which is then transformed into rock by geological processes.
Mineral Content
Amphibole, Augite, Bronzite, Chromite, Diopside, Enstatite, Garnet, Hornblende, Hypersthene, Magnetite, Pyroxene
Calcite, Clay, Clay Minerals, Quartz, Sand
Compound Content
Aluminium Oxide, CaO, Chromium(III) Oxide, Iron(III) Oxide, Potassium Oxide, MgO, Sodium Oxide, Silicon Dioxide, Sulfur Trioxide
Ca, NaCl, CaO
Types of Metamorphism
Burial Metamorphism, Impact Metamorphism
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Types of Weathering
Biological Weathering, Chemical Weathering, Mechanical Weathering
Biological Weathering, Chemical Weathering
Types of Erosion
Chemical Erosion, Coastal Erosion, Glacier Erosion, Water Erosion, Wind Erosion
Chemical Erosion, Coastal Erosion, Water Erosion
Grain Size
Coarse Grained
Very fine-grained
Streak
White, Greenish White or Grey
White
Porosity
Less Porous
Highly Porous
Luster
Dull to Vitreous to Submetallic
Dull
Specific Gravity
3.2-3.5
2.3-2.4
Transparency
Opaque
Opaque
Density
3.1-3.6 g/cm3
2.49-2.50 g/cm3
Resistance
Impact Resistant, Pressure Resistant, Wear Resistant
Heat Resistant
Deposits in Eastern Continents
Asia
India, Russia
Brunei, India, Indonesia, Malaysia, Singapore, Thailand, Vietnam
Africa
South Africa
Cameroon, Chad, Ghana, Kenya, Malawi, Sudan, Tanzania, Togo, Zambia, Zimbabwe
Europe
Germany, Greece, Italy, Scotland, Turkey
England, France, Germany, Spain, United Kingdom
Deposits in Western Continents
North America
Canada, USA
Canada, USA
South America
Brazil, Colombia, Venezuela
Colombia
Deposits in Oceania Continent
Australia
New Zealand, Queensland
Adelaide, New Zealand, Queensland, Victoria, Yorke Peninsula
All about Websterite and Chalk Properties
Know all about Websterite and Chalk properties here. All properties of rocks are important as they define the type of rock and its application. Websterite belongs to Igneous Rocks while Chalk belongs to Sedimentary Rocks.Texture of Websterite is Clastic, Granular, Phaneritic, Porphyritic whereas that of Chalk is Clastic or Non-Clastic. Websterite appears Layered, Banded, Veined and Shiny and Chalk appears Soft. The luster of Websterite is dull to vitreous to submetallic while that of Chalk is dull. Websterite is available in black to grey, bluish - grey, dark greenish - grey, green, light greenish grey colors whereas Chalk is available in grey, white, yellow colors. The commercial uses of Websterite are cemetery markers, commemorative tablets, creating artwork, laboratory bench tops, jewelry, sea defence, tombstones and that 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.