Hornfels

Greywacke

Hornfels and Greywacke

Hornfels

Greywacke

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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

Greywacke is defined as a dark coarse-grained sandstone rock which contains more than 15 per cent clay

History

Origin

New Zealand

Discoverer

Unknown

Etymology

From German which means hornstone

From German Grauwacke, from grau grey + wacke

Class

Metamorphic Rocks

Sedimentary Rocks

Sub-Class

Durable Rock, Soft Rock

Durable Rock, Hard Rock

Family

Group

Other Categories

Fine Grained Rock, Opaque Rock

Texture

Granular, Platy

Clastic

Color

Brown, Dark Greenish - Grey, Green, Reddish Brown

Beige, Black, Brown, Cream, Dark Brown, Green, Grey, Light Green, Light to Dark Grey, Pink, Red, White, Yellow

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

Decorative Aggregates, Floor Tiles, Flooring, Homes, Interior Decoration

Exterior Uses

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

Other Architectural Uses

Curbing

Curbing, Whetstones

Industry

Construction Industry

for Road Aggregate, Roadstone

Building houses or walls, Cement Manufacture, Construction Aggregate, for Road Aggregate, Raw material for the manufacture of mortar

Medical Industry

Antiquity Uses

Artifacts, Monuments

Artifacts, Sculpture, Small Figurines

Other Uses

Commercial Uses

Cemetery Markers, Commemorative Tablets, Creating Artwork

As armour rock for sea walls, Petroleum reservoirs, Sea Defence, Tombstones

Types

Biotite hornfels

Greywacke

Features

Smooth to touch

Available in Lots of Colors and Patterns, Generally rough to touch, Non-vesicular, Veined

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.

Graywacke rock is a type of sedimentary rock, which is also known as immature sandstone, which is indurated, dark grey and consisting of poorly sorted angular to sub-angular, sand-sized grains.

Composition

Mineral Content

Andalusite

Augite, Biotite, Calcite, Chlorite, Clay, Clay Minerals, Feldspar, Micas, Muscovite or Illite, Plagioclase, Pyroxene, Quartz

Compound Content

Fe, Mg

Aluminium Oxide, NaCl, CaO, Chromium(III) Oxide, Iron(III) Oxide, FeO, Potassium Oxide, Magnesium Carbonate, MgO, MnO, Sodium Oxide, Phosphorus Pentoxide, Silicon Dioxide, Titanium Dioxide

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

Coastal Erosion, Sea Erosion, Wind Erosion

Properties

Physical Properties

Hardness

2-36-7

1 7

👆🏻

Grain Size

Fine Grained

Angular and Fine

Fracture

Conchoidal

Streak

White

Porosity

Highly Porous

Luster

Shiny

Dull

Compressive Strength

5.80 N/mm²120.00 N/mm²

0.15 450

👆🏻

Cleavage

Perfect

Toughness

2.6

Specific Gravity

3.4-3.92.2-2.8

0 8.4

👆🏻

Transparency

Opaque

Density

0.25-0.30 g/cm³2.6-2.61 g/cm³

0 1400

👆🏻

Thermal Properties

Specific Heat Capacity

0.84 kJ/Kg K0.71 kJ/Kg K

0.14 3.2

👆🏻

Resistance

Heat Resistant, Impact Resistant, Pressure Resistant

Reserves

Deposits in Eastern Continents

Asia

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

China, India, Kazakhstan, Mongolia, Russia, Uzbekistan

Africa

Cameroon, East Africa, Tanzania, Western Africa

Namibia, Nigeria, South Africa

Europe

United Kingdom

Austria, Denmark, Germany, Great Britain, Netherlands, Norway, Poland, Sweden, Switzerland, United Kingdom

Others

Greenland

Deposits in Western Continents

North America

Canada, USA

South America

Bolivia, Brazil, Colombia, Ecuador

Brazil

Deposits in Oceania Continent

Australia

New South Wales, New Zealand, Queensland, Western Australia

New South Wales, New Zealand

All about Hornfels and Greywacke Properties

Know all about Hornfels and Greywacke properties here. All properties of rocks are important as they define the type of rock and its application. Hornfels belongs to Metamorphic Rocks while Greywacke belongs to Sedimentary Rocks.Texture of Hornfels is Granular, Platy whereas that of Greywacke is Clastic. Hornfels appears Dull and Greywacke appears Dull. The luster of Hornfels is shiny while that of Greywacke is dull. Hornfels is available in brown, dark greenish - grey, green, reddish brown colors whereas Greywacke is available in beige, black, brown, cream, dark brown, green, grey, light green, light to dark grey, pink, red, white, yellow colors. The commercial uses of Hornfels are cemetery markers, commemorative tablets, creating artwork and that of Greywacke are as armour rock for sea walls, petroleum reservoirs, sea defence, tombstones.