Hornfels

Chalk

Hornfels and Chalk

Hornfels

Chalk

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Definition

Hornfels is a metamorphic rock formed by the contact between mudstone or other clay rich rock, and a hot igneous body, and represents a heat altered equivalent of the original rock

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

History

Origin

New Zealand

Discoverer

Unknown

Etymology

From German which means hornstone

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

Class

Metamorphic Rocks

Sedimentary Rocks

Sub-Class

Durable Rock, Soft Rock

Family

Group

Other Categories

Fine Grained Rock, Opaque Rock

Texture

Granular, Platy

Clastic or Non-Clastic

Color

Brown, Dark Greenish - Grey, Green, Reddish Brown

Grey, White, Yellow

Maintenance

Less

Durability

Durable

Water Resistant

✔ ✘

Scratch Resistant

✔ ✘

Stain Resistant

✔ ✘

Wind Resistant

✔ ✘

Acid Resistant

✔ ✘

Appearance

Dull

Soft

Uses

Architecture

Interior Uses

Decorative Aggregates, Flooring, Homes, Interior Decoration

Decorative Aggregates, Homes, Interior Decoration

Exterior Uses

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

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

Other Architectural Uses

Curbing

Powder

Industry

Construction Industry

for Road Aggregate, Roadstone

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

Medical Industry

Antiquity Uses

Artifacts, Monuments

Artifacts, Monuments, Sculpture, Small Figurines

Other Uses

Commercial Uses

Cemetery Markers, Commemorative Tablets, Creating Artwork

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

Biotite hornfels

Chalk Marl and Marl

Features

Smooth to touch

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

Archaeological Significance

Monuments

Famous Monuments

Sculpture

Famous Sculptures

Pictographs

Petroglyphs

Figurines

Fossils

Absent

Present

Formation

Due to change in environmental conditions, rocks are heated and pressurized deep inside the Earth's surface. Hornfels is formed from the extreme heat caused by magma or by the intense collisions and friction of tectonic plates.

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

Composition

Mineral Content

Andalusite

Calcite, Clay, Clay Minerals, Quartz, Sand

Compound Content

Fe, Mg

Ca, NaCl, CaO

Transformation

Metamorphism

✔ ✘

Types of Metamorphism

Weathering

✔ ✘

Types of Weathering

Biological Weathering

Biological Weathering, Chemical Weathering

Erosion

✔ ✘

Types of Erosion

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

Chemical Erosion, Coastal Erosion, Water Erosion

Properties

Physical Properties

Hardness

2-31

1 7

👆🏻

Grain Size

Fine Grained

Very fine-grained

Fracture

Conchoidal

Streak

White

Porosity

Highly Porous

Luster

Shiny

Dull

Compressive Strength

5.80 N/mm²5.00 N/mm²

0.15 450

👆🏻

Cleavage

Perfect

Toughness

Specific Gravity

3.4-3.92.3-2.4

0 8.4

👆🏻

Transparency

Opaque

Density

0.25-0.30 g/cm³2.49-2.50 g/cm³

0 1400

👆🏻

Thermal Properties

Specific Heat Capacity

0.84 kJ/Kg K0.90 kJ/Kg K

0.14 3.2

👆🏻

Resistance

Heat Resistant, Impact Resistant, Pressure Resistant

Heat Resistant

Reserves

Deposits in Eastern Continents

Asia

Bangladesh, Bhutan, China, India, North Korea, Qatar, Russia, Saudi Arabia, South Korea, Thailand

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

Africa

Cameroon, East Africa, Tanzania, Western Africa

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

Europe

United Kingdom

England, France, Germany, Spain, United Kingdom

Others

Deposits in Western Continents

North America

Canada, USA

South America

Bolivia, Brazil, Colombia, Ecuador

Colombia

Deposits in Oceania Continent

Australia

New South Wales, New Zealand, Queensland, Western Australia

Adelaide, New Zealand, Queensland, Victoria, Yorke Peninsula

All about Hornfels and Chalk Properties

Know all about Hornfels and Chalk properties here. All properties of rocks are important as they define the type of rock and its application. Hornfels belongs to Metamorphic Rocks while Chalk belongs to Sedimentary Rocks.Texture of Hornfels is Granular, Platy whereas that of Chalk is Clastic or Non-Clastic. Hornfels appears Dull and Chalk appears Soft. The luster of Hornfels is shiny while that of Chalk is dull. Hornfels is available in brown, dark greenish - grey, green, reddish brown colors whereas Chalk is available in grey, white, yellow colors. The commercial uses of Hornfels are cemetery markers, commemorative tablets, creating artwork 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.