Greywacke

Hornfels

Greywacke and Hornfels

Greywacke

Hornfels

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Definition

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

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

History

Origin

New Zealand

Discoverer

Unknown

Etymology

From German Grauwacke, from grau grey + wacke

From German which means hornstone

Class

Sedimentary Rocks

Metamorphic Rocks

Sub-Class

Durable Rock, Hard Rock

Durable Rock, Soft Rock

Family

Group

Other Categories

Fine Grained Rock, Opaque Rock

Texture

Clastic

Granular, Platy

Color

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

Brown, Dark Greenish - Grey, Green, Reddish Brown

Maintenance

Less

Durability

Durable

Water Resistant

✔ ✘

Scratch Resistant

✔ ✘

Stain Resistant

✔ ✘

Wind Resistant

✔ ✘

Acid Resistant

✔ ✘

Appearance

Dull

Uses

Architecture

Interior Uses

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

Decorative Aggregates, Flooring, Homes, Interior Decoration

Exterior Uses

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

Other Architectural Uses

Curbing, Whetstones

Curbing

Industry

Construction Industry

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

for Road Aggregate, Roadstone

Medical Industry

Antiquity Uses

Artifacts, Sculpture, Small Figurines

Artifacts, Monuments

Other Uses

Commercial Uses

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

Cemetery Markers, Commemorative Tablets, Creating Artwork

Types

Greywacke

Biotite hornfels

Features

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

Smooth to touch

Archaeological Significance

Monuments

Famous Monuments

Sculpture

Famous Sculptures

Pictographs

Petroglyphs

Figurines

Fossils

Present

Absent

Formation

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.

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.

Composition

Mineral Content

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

Andalusite

Compound Content

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

Fe, Mg

Transformation

Metamorphism

✔ ✘

Types of Metamorphism

Weathering

✔ ✘

Types of Weathering

Biological Weathering, Chemical Weathering

Biological Weathering

Erosion

✔ ✘

Types of Erosion

Coastal Erosion, Sea Erosion, Wind Erosion

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

Properties

Physical Properties

Hardness

6-72-3

1 7

👆🏻

Grain Size

Angular and Fine

Fine Grained

Fracture

Conchoidal

Streak

White

Porosity

Highly Porous

Luster

Dull

Shiny

Compressive Strength

120.00 N/mm²5.80 N/mm²

0.15 450

👆🏻

Cleavage

Perfect

Toughness

2.6

Specific Gravity

2.2-2.83.4-3.9

0 8.4

👆🏻

Transparency

Opaque

Density

2.6-2.61 g/cm³0.25-0.30 g/cm³

0 1400

👆🏻

Thermal Properties

Specific Heat Capacity

0.71 kJ/Kg K0.84 kJ/Kg K

0.14 3.2

👆🏻

Resistance

Heat Resistant, Impact Resistant, Pressure Resistant

Reserves

Deposits in Eastern Continents

Asia

China, India, Kazakhstan, Mongolia, Russia, Uzbekistan

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

Africa

Namibia, Nigeria, South Africa

Cameroon, East Africa, Tanzania, Western Africa

Europe

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

United Kingdom

Others

Greenland

Deposits in Western Continents

North America

Canada, USA

South America

Brazil

Bolivia, Brazil, Colombia, Ecuador

Deposits in Oceania Continent

Australia

New South Wales, New Zealand

New South Wales, New Zealand, Queensland, Western Australia

All about Greywacke and Hornfels Properties

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