Chalk

Picrite

Chalk and Picrite

Chalk

Picrite

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Definition

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

Picrite is a variety of high-magnesium olivine basalt that is very rich in the mineral olivine

History

Origin

Hawaii Islands

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 Greek pikros bitter + -ite, 19th century

Class

Sedimentary Rocks

Igneous Rocks

Sub-Class

Durable Rock, Soft Rock

Durable Rock, Hard Rock

Family

Group

Volcanic

Other Categories

Fine Grained Rock, Opaque Rock

Texture

Clastic or Non-Clastic

Earthy, Rough

Color

Grey, White, Yellow

Black, Brown, Green, Grey, Pink, White, Yellow

Maintenance

Less

Durability

Durable

Water Resistant

✔ ✘

Scratch Resistant

✔ ✘

Stain Resistant

✔ ✘

Wind Resistant

✔ ✘

Acid Resistant

✔ ✘

Appearance

Soft

Rough and Shiny

Uses

Architecture

Interior Uses

Decorative Aggregates, Homes, Interior Decoration

Countertops, Decorative Aggregates, Homes, Interior Decoration

Exterior Uses

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

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

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

As a Sintering Agent in Steel Industry to process Iron Ore, Cement Manufacture, for Road Aggregate, Manufacture of Magnesium and Dolomite Refractories, Roadstone, Used for flooring, stair treads, borders and window sills.

Medical Industry

Antiquity Uses

Artifacts, Monuments, Sculpture, Small Figurines

Artifacts, Monuments, Sculpture

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

As a Feed Additive for Livestock, As armour rock for sea walls, Metallurgical Flux, Pottery, Source of Magnesia (MgO)

Types

Chalk Marl and Marl

Oceanite

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

Monuments

Famous Monuments

Sculpture

Famous Sculptures

Pictographs

Petroglyphs

Figurines

Fossils

Present

Absent

Formation

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

Picrite is a fine-grained, hard rock which is a type of metasomatite, essentially altered basalt. It forms with or without crystallization, either below the surface as intrusive rocks or on the surface as extrusive rocks.

Composition

Mineral Content

Calcite, Clay, Clay Minerals, Quartz, Sand

Biotite, Olivine, Plagioclase, Pyrrhotite

Compound Content

Ca, NaCl, CaO

Al, CaO, Carbon Dioxide, Mg, MgO

Transformation

Metamorphism

✔ ✘

Types of Metamorphism

Burial Metamorphism, Cataclastic Metamorphism, Impact Metamorphism, Regional Metamorphism

Weathering

✔ ✘

Types of Weathering

Biological Weathering, Chemical Weathering

Biological Weathering

Erosion

✔ ✘

Types of Erosion

Chemical Erosion, Coastal Erosion, Water Erosion

Chemical Erosion, Coastal Erosion, Glacier Erosion, Sea Erosion, Water Erosion, Wind Erosion

Properties

Physical Properties

Hardness

16.8

1 7

👆🏻

Grain Size

Very fine-grained

Fine Grained

Fracture

Uneven

Streak

White

White, Greenish White or Grey

Porosity

Highly Porous

Less Porous

Luster

Dull

Subvitreous to Dull

Compressive Strength

5.00 N/mm²189.00 N/mm²

0.15 450

👆🏻

Cleavage

Toughness

2.1

Specific Gravity

2.3-2.42.75-2.92

0 8.4

👆🏻

Transparency

Opaque

Density

2.49-2.50 g/cm³1.5-2.5 g/cm³

0 1400

👆🏻

Thermal Properties

Specific Heat Capacity

0.90 kJ/Kg K0.88 kJ/Kg K

0.14 3.2

👆🏻

Resistance

Heat Resistant

Reserves

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

Others

Deposits in Western Continents

North America

Canada, USA

South America

Colombia

Brazil

Deposits in Oceania Continent

Australia

Adelaide, New Zealand, Queensland, Victoria, Yorke Peninsula

All about Chalk and Picrite Properties

Know all about Chalk and Picrite properties here. All properties of rocks are important as they define the type of rock and its application. Chalk belongs to Sedimentary Rocks while Picrite belongs to Igneous Rocks.Texture of Chalk is Clastic or Non-Clastic whereas that of Picrite is Earthy, Rough. Chalk appears Soft and Picrite appears Rough and Shiny. The luster of Chalk is dull while that of Picrite is subvitreous to dull. Chalk is available in grey, white, yellow colors whereas Picrite is available in black, brown, green, grey, pink, white, yellow 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 Picrite are as a feed additive for livestock, as armour rock for sea walls, metallurgical flux, pottery, source of magnesia (mgo).