Hornfels

Slate

Hornfels and Slate

Hornfels

Slate

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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

Slate is a fine-grained, foliated, homogeneous metamorphic rock derived from an original shale-type sedimentary rock composed of clay or volcanic ash through low-grade regional metamorphism

History

Origin

New Zealand

England

Discoverer

Unknown

Abraham Gottlob Werner

Etymology

From German which means hornstone

From Old French esclate, from esclat (French éclat)

Class

Metamorphic Rocks

Sub-Class

Durable Rock, Soft Rock

Durable Rock, Medium Hardness Rock

Family

Group

Other Categories

Fine Grained Rock, Opaque Rock

Texture

Granular, Platy

Foliated

Color

Brown, Dark Greenish - Grey, Green, Reddish Brown

Black, Brown, Buff, Green, Light to Dark Grey, Purple, Red, Shades of Blue

Maintenance

Less

Durability

Durable

Water Resistant

✔ ✘

Scratch Resistant

✔ ✘

Stain Resistant

✔ ✘

Wind Resistant

✔ ✘

Acid Resistant

✔ ✘

Appearance

Dull

Uses

Architecture

Interior Uses

Decorative Aggregates, Flooring, Homes, Interior Decoration

Bathrooms, Decorative Aggregates, Entryways, Floor Tiles, Flooring, Homes, Hotels, Interior Decoration, Kitchens, Stair Treads

Exterior Uses

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

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

Other Architectural Uses

Curbing

Industry

Construction Industry

for Road Aggregate, Roadstone

As Dimension Stone

Medical Industry

Antiquity Uses

Artifacts, Monuments

Artifacts, Monuments, Sculpture, Small Figurines

Other Uses

Commercial Uses

Cemetery Markers, Commemorative Tablets, Creating Artwork

Blackboards, Commemorative Tablets, Laboratory bench tops, Standard material for the bed of Billiard table, Standard material for the beds of Pool and Snooker table, Tombstones, Used in aquariums, Writing Slates

Types

Biotite hornfels

Phyllite, Schist, and Slate

Features

Smooth to touch

Easily splits into thin plates, Surfaces are often shiny, Very fine grained rock

Archaeological Significance

Monuments

Famous Monuments

Sculpture

Famous Sculptures

Pictographs

Petroglyphs

Figurines

Fossils

Absent

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.

Slate is a low grade metamorphic rock that is generally formed by metamorphosis of mudstone or shale, under relatively low pressure and temperature conditions.

Composition

Mineral Content

Andalusite

Apatite, Biotite, Chlorite, Feldspar, Graphite, Hematite, Kaolinite, Magnetite, Pyrite, Tourmaline, Zircon

Compound Content

Fe, Mg

Aluminium Oxide, CaO, Iron(III) Oxide, Potassium Oxide, MgO, Sodium Oxide, Silicon Dioxide, Titanium Dioxide

Transformation

Metamorphism

✔ ✘

Types of Metamorphism

Burial Metamorphism, Cataclastic Metamorphism, Regional 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

Coastal Erosion, Glacier Erosion, Water Erosion, Wind Erosion

Properties

Physical Properties

Hardness

2-33-4

1 7

👆🏻

Grain Size

Fine Grained

Very fine-grained

Fracture

Conchoidal

Splintery

Streak

Light to dark brown

Porosity

Highly Porous

Less Porous

Luster

Shiny

Dull

Compressive Strength

5.80 N/mm²30.00 N/mm²

0.15 450

👆🏻

Cleavage

Perfect

Slaty

Toughness

1.2

Specific Gravity

3.4-3.92.65-2.8

0 8.4

👆🏻

Transparency

Opaque

Density

0.25-0.30 g/cm³2.6-2.8 g/cm³

0 1400

👆🏻

Thermal Properties

Specific Heat Capacity

0.84 kJ/Kg K0.76 kJ/Kg K

0.14 3.2

👆🏻

Resistance

Heat Resistant, Impact Resistant, Pressure Resistant

Heat Resistant, Impact Resistant, Pressure Resistant, Wear Resistant

Reserves

Deposits in Eastern Continents

Asia

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

China, India, Turkey

Africa

Cameroon, East Africa, Tanzania, Western Africa

Europe

United Kingdom

Belgium, France, Germany, Italy, Norway, Portugal, Spain, United Kingdom

Others

Arctic

Deposits in Western Continents

North America

Canada, USA

USA

South America

Bolivia, Brazil, Colombia, Ecuador

Brazil

Deposits in Oceania Continent

Australia

New South Wales, New Zealand, Queensland, Western Australia

All about Hornfels and Slate Properties

Know all about Hornfels and Slate properties here. All properties of rocks are important as they define the type of rock and its application. Hornfels and Slate belong to Metamorphic Rocks.Texture of Hornfels is Granular, Platy whereas that of Slate is Foliated. Hornfels appears Dull and Slate appears Dull. The luster of Hornfels is shiny while that of Slate is dull. Hornfels is available in brown, dark greenish - grey, green, reddish brown colors whereas Slate is available in black, brown, buff, green, light to dark grey, purple, red, shades of blue colors. The commercial uses of Hornfels are cemetery markers, commemorative tablets, creating artwork and that of Slate are blackboards, commemorative tablets, laboratory bench tops, standard material for the bed of billiard table, standard material for the beds of pool and snooker table, tombstones, used in aquariums, writing slates.