Hornfels

Variolite

Hornfels and Variolite

Hornfels

Variolite

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1 Definition

1.1 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

Variolites are a group of dark green basic igneous rocks which exhibit pale colored spots, or spherules, especially on weathered surfaces, that give them a pockmarked appearance

1.2 History

1.2.1 Origin

New Zealand

France

1.2.2 Discoverer

Unknown

1.3 Etymology

From German which means hornstone

From Latin varius, speckled, variegated

1.4 Class

Metamorphic Rocks

Igneous Rocks

1.4.1 Sub-Class

Durable Rock, Soft Rock

Durable Rock, Hard Rock

1.5 Family

1.5.1 Group

Not Applicable

Volcanic

1.6 Other Categories

Fine Grained Rock, Opaque Rock

Opaque Rock

2 Texture

2.1 Texture

Granular, Platy

Glassy, Massive, Porphyritic, Scoriaceous, Vesicular

2.2 Color

Brown, Dark Greenish - Grey, Green, Reddish Brown

Black, Brown, Light to Dark Grey

2.3 Maintenance

Less

2.4 Durability

Durable

2.4.1 Water Resistant

✔ ✘

2.4.2 Scratch Resistant

✔ ✘

2.4.3 Stain Resistant

✔ ✘

2.4.4 Wind Resistant

✔ ✘

2.4.5 Acid Resistant

✔ ✘

2.5 Appearance

Dull

Dull and Soft

3 Uses

3.1 Architecture

3.1.1 Interior Uses

Decorative Aggregates, Flooring, Homes, Interior Decoration

Floor Tiles, Flooring, Homes, Hotels, Kitchens

3.1.2 Exterior Uses

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

Garden Decoration, Office Buildings

3.1.3 Other Architectural Uses

Curbing

3.2 Industry

3.2.1 Construction Industry

for Road Aggregate, Roadstone

As Dimension Stone, Cobblestones, Rail Track Ballast, Roadstone

3.2.2 Medical Industry

Not Yet Used

3.3 Antiquity Uses

Artifacts, Monuments

Artifacts, Monuments, Sculpture

3.4 Other Uses

3.4.1 Commercial Uses

Cemetery Markers, Commemorative Tablets, Creating Artwork

Cemetery Markers, Creating Artwork

4 Types

4.1 Types

Biotite hornfels

Not Available

4.2 Features

Smooth to touch

Has High structural resistance against erosion and climate, Very fine grained rock

4.3 Archaeological Significance

4.3.1 Monuments

Used

4.3.2 Famous Monuments

Data Not Available

4.3.3 Sculpture

Not Yet Used

Used

4.3.4 Famous Sculptures

Not Applicable

Data Not Available

4.3.5 Pictographs

Used

4.3.6 Petroglyphs

Used

4.3.7 Figurines

Not Yet Used

Used

4.4 Fossils

Absent

5 Formation

5.1 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.

Variolites are a group of dark green basic igneous rocks that exhibit pale colored spots on weathered surfaces that give them a pockmarked appearance.

5.2 Composition

5.2.1 Mineral Content

Andalusite

Olivine, Plagioclase, Pyroxene

5.2.2 Compound Content

Fe, Mg

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

5.3 Transformation

5.3.1 Metamorphism

✔ ✘

5.3.2 Types of Metamorphism

Not Applicable

Burial Metamorphism, Cataclastic Metamorphism, Contact Metamorphism, Hydrothermal Metamorphism, Impact Metamorphism, Regional Metamorphism

5.3.3 Weathering

✔ ✘

5.3.4 Types of Weathering

Biological Weathering

Biological Weathering, Chemical Weathering, Mechanical Weathering

5.3.5 Erosion

✔ ✘

5.3.6 Types of Erosion

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

Not Applicable

6 Properties

6.1 Physical Properties

6.1.1 Hardness

2-36

1 7

6.1.2 Grain Size

Fine Grained

Not Applicable

6.1.3 Fracture

Conchoidal

6.1.4 Streak

Unknown

White to Grey

6.1.5 Porosity

Highly Porous

Less Porous

6.1.6 Luster

Shiny

Not Available

6.1.7 Compressive Strength

5.80 N/mm²37.50 N/mm²

0.15 450

6.1.8 Cleavage

Perfect

Not Available

6.1.9 Toughness

Not Yet Found

2.3

6.1.10 Specific Gravity

3.4-3.92.8-3

0 8.4

6.1.11 Transparency

Opaque

6.1.12 Density

0.25-0.30 g/cm³2.9-3.1 g/cm³

0 1400

6.2 Thermal Properties

6.2.1 Specific Heat Capacity

0.84 kJ/Kg K0.84 kJ/Kg K

0.14 3.2

6.2.2 Resistance

Heat Resistant, Impact Resistant, Pressure Resistant

Heat Resistant, Pressure Resistant, Wear Resistant

7 Reserves

7.1 Deposits in Eastern Continents

7.1.1 Asia

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

India, Russia

7.1.2 Africa

Cameroon, East Africa, Tanzania, Western Africa

South Africa

7.1.3 Europe

United Kingdom

Iceland

7.1.4 Others

Not Yet Found

7.2 Deposits in Western Continents

7.2.1 North America

Canada, USA

7.2.2 South America

Bolivia, Brazil, Colombia, Ecuador

Brazil

7.3 Deposits in Oceania Continent

7.3.1 Australia

New South Wales, New Zealand, Queensland, Western Australia

Not Yet Found

All about Hornfels and Variolite Properties

Know all about Hornfels and Variolite properties here. All properties of rocks are important as they define the type of rock and its application. Hornfels belongs to Metamorphic Rocks while Variolite belongs to Igneous Rocks.Texture of Hornfels is Granular, Platy whereas that of Variolite is Glassy, Massive, Porphyritic, Scoriaceous, Vesicular. Hornfels appears Dull and Variolite appears Dull and Soft. The luster of Hornfels is shiny while that of Variolite is not available. Hornfels is available in brown, dark greenish - grey, green, reddish brown colors whereas Variolite is available in black, brown, light to dark grey colors. The commercial uses of Hornfels and Variolite are cemetery markers, commemorative tablets, creating artwork.