Hornfels

Shale

Hornfels and Shale

Hornfels

Shale

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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

Shale is a fine-grained sedimentary rock which is formed by the compaction of silt and clay-size mineral particles

History

Origin

New Zealand

Discoverer

Unknown

Johann Gottlob Lehmann

Etymology

From German which means hornstone

From German Schalstein laminated limestone, and Schalgebirge layer of stone in stratified rock. From Old English scealu in its base sense of- thing that divides or separate,

Class

Metamorphic Rocks

Sedimentary Rocks

Sub-Class

Durable Rock, Soft Rock

Durable Rock, Medium Hardness Rock

Family

Group

Other Categories

Fine Grained Rock, Opaque Rock

Texture

Granular, Platy

Clastic, Splintery

Color

Brown, Dark Greenish - Grey, Green, Reddish Brown

Black, Brown, Buff, Green, Grey, Red, Yellow

Maintenance

Less

Durability

Durable

Water Resistant

✔ ✘

Scratch Resistant

✔ ✘

Stain Resistant

✔ ✘

Wind Resistant

✔ ✘

Acid Resistant

✔ ✘

Appearance

Dull

Muddy

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, Office Buildings

Other Architectural Uses

Curbing

Industry

Construction Industry

for Road Aggregate, Roadstone

Cement Manufacture, Construction Aggregate, for Road Aggregate, Making natural cement, Raw material for the manufacture of mortar

Medical Industry

Antiquity Uses

Artifacts, Monuments

Artifacts, Sculpture

Other Uses

Commercial Uses

Cemetery Markers, Commemorative Tablets, Creating Artwork

Creating Artwork, Pottery

Types

Biotite hornfels

Red Shale, Black Shale, Green Shale, Grey Shale and Yellow Shale

Features

Smooth to touch

Easily splits into thin plates, Generally rough to touch, Very fine grained rock

Archaeological Significance

Monuments

Famous Monuments

Jantar Mantar in India

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.

Shale forms when very fine-grained clay particles are deposited in water which settle at the bottom of water bodies. They are later compacted hence forming shale.

Composition

Mineral Content

Andalusite

Albite, Biotite, Calcite, Chert, Chlorite, Dolomite, Hematite, Micas, Muscovite or Illite, Pyrite, Quartz, Silica, Sulfides

Compound Content

Fe, Mg

Ca, Fe, Mg, Silicon Dioxide, Sodium

Transformation

Metamorphism

✔ ✘

Types of Metamorphism

Weathering

✔ ✘

Types of Weathering

Biological Weathering

Biological Weathering, Chemical Weathering, Mechanical Weathering

Erosion

✔ ✘

Types of Erosion

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

Chemical Erosion, Coastal Erosion, Glacier Erosion

Properties

Physical Properties

Hardness

2-33

1 7

👆🏻

Grain Size

Fine Grained

Very fine-grained

Fracture

Conchoidal

Streak

White

Porosity

Highly Porous

Luster

Shiny

Dull

Compressive Strength

5.80 N/mm²95.00 N/mm²

0.15 450

👆🏻

Cleavage

Perfect

Slaty

Toughness

2.6

Specific Gravity

3.4-3.92.2-2.8

0 8.4

👆🏻

Transparency

Opaque

Density

0.25-0.30 g/cm³2.4-2.8 g/cm³

0 1400

👆🏻

Thermal Properties

Specific Heat Capacity

0.84 kJ/Kg K0.39 kJ/Kg K

0.14 3.2

👆🏻

Resistance

Heat Resistant, Impact Resistant, Pressure Resistant

Heat Resistant, Impact Resistant

Reserves

Deposits in Eastern Continents

Asia

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

Bangladesh, China, India, Russia

Africa

Cameroon, East Africa, Tanzania, Western Africa

Ethiopia, Kenya, Morocco, South Africa, Tanzania

Europe

United Kingdom

Austria, France, Germany, Greece, Italy, Romania, Scotland, Spain, Switzerland

Others

Deposits in Western Continents

North America

Canada, USA

USA

South America

Bolivia, Brazil, Colombia, Ecuador

Bolivia, Chile, Colombia, Ecuador, Peru, Venezuela

Deposits in Oceania Continent

Australia

New South Wales, New Zealand, Queensland, Western Australia

New South Wales, New Zealand, Queensland, Victoria, Western Australia

All about Hornfels and Shale Properties

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