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Hornfels
Hornfels

Variolite
Variolite



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Hornfels
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Variolite

Hornfels vs Variolite

Definition

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

History

Origin

New Zealand
France

Discoverer

Unknown
Unknown

Etymology

From German which means hornstone
From Latin varius, speckled, variegated

Class

Metamorphic Rocks
Igneous Rocks

Sub-Class

Durable Rock, Soft Rock
Durable Rock, Hard Rock

Family

Group

-
Volcanic

Other Categories

Fine Grained Rock, Opaque Rock
Opaque Rock

Texture

Texture

Granular, Platy
Glassy, Massive, Porphyritic, Scoriaceous, Vesicular

Color

Brown, Dark Greenish - Grey, Green, Reddish Brown
Black, Brown, Light to Dark Grey

Maintenance

Less
Less

Durability

Durable
Durable

Water Resistant

Scratch Resistant

Stain Resistant

Wind Resistant

Acid Resistant

Appearance

Dull
Dull and Soft

Uses

Architecture

Interior Uses

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

Exterior Uses

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

Other Architectural Uses

Curbing
Curbing

Industry

Construction Industry

for Road Aggregate, Roadstone
As Dimension Stone, Cobblestones, Rail Track Ballast, Roadstone

Medical Industry

-
-

Antiquity Uses

Artifacts, Monuments
Artifacts, Monuments, Sculpture

Other Uses

Commercial Uses

Cemetery Markers, Commemorative Tablets, Creating Artwork
Cemetery Markers, Creating Artwork

Types

Types

Biotite hornfels
Metamorphic rock

Features

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

Archaeological Significance

Monuments

-
-

Famous Monuments

-
-

Sculpture

-
-

Famous Sculptures

-
-

Pictographs

-
-

Petroglyphs

-
-

Figurines

-
-

Fossils

Absent
Absent

Formation

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.

Composition

Mineral Content

Andalusite
Olivine, Plagioclase, Pyroxene

Compound Content

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

Transformation

Metamorphism

Types of Metamorphism

-
Burial Metamorphism, Cataclastic Metamorphism, Contact Metamorphism, Hydrothermal Metamorphism, Impact 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
-

Properties

Physical Properties

Hardness

2-36
1 7
👆🏻

Grain Size

Fine Grained
-

Fracture

Conchoidal
Conchoidal

Streak

-
White to Grey

Porosity

Highly Porous
Less Porous

Luster

Shiny
-

Compressive Strength

5.80 N/mm237.50 N/mm2
0.15 450
👆🏻

Cleavage

Perfect
-

Toughness

-
2.3

Specific Gravity

3.4-3.92.8-3
0 8.4
👆🏻

Transparency

Opaque
Opaque

Density

0.25-0.30 g/cm32.9-3.1 g/cm3
0 1400
👆🏻

Thermal Properties

Specific Heat Capacity

0.84 kJ/Kg K0.84 kJ/Kg K
0.14 3.2
👆🏻

Resistance

Heat Resistant, Impact Resistant, Pressure Resistant
Heat Resistant, Pressure Resistant, Wear Resistant

Reserves

Deposits in Eastern Continents

Asia

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

Africa

Cameroon, East Africa, Tanzania, Western Africa
South Africa

Europe

United Kingdom
Iceland

Others

-
-

Deposits in Western Continents

North America

Canada, USA
Canada, USA

South America

Bolivia, Brazil, Colombia, Ecuador
Brazil

Deposits in Oceania Continent

Australia

New South Wales, New Zealand, Queensland, Western Australia
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Hornfels vs Variolite Information

Earth’s outer layer is covered by rocks and these rocks have different physical and chemical properties. As two rocks are not same, it’s fun to compare them. You can also know more about Hornfels and Variolite Reserves. 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. These rocks are composed of many distinct minerals. The process of formation of rocks is different for various rocks. Rocks are quarried from many years for various purposes. You can check out Hornfels vs Variolite information and Hornfels vs Variolite characteristics in the upcoming sections.

Hornfels vs Variolite Characteristics

Though some rocks look identical, they have certain characteristics which distinguish them from others. Characteristics of rocks include texture, appearance, color, fracture, streak, hardness etc. Hornfels vs Variolite characteristics assist us to distinguish and recognize rocks. Also you can check about Properties of Hornfels and Properties of Variolite. Learn more about Hornfels vs Variolite in the next section. The interior uses of Hornfels include Decorative aggregates, Flooring, Homes and Interior decoration whereas the interior uses of Variolite include Floor tiles, Flooring, Homes, Hotels and Kitchens. Due to some exceptional properties of Hornfels and Variolite, they have various applications in construction industry. The uses of Hornfels in construction industry include For road aggregate, Roadstone and that of Variolite include As dimension stone, Cobblestones, Rail track ballast, Roadstone.

More about Hornfels and Variolite

Here you can know more about Hornfels and Variolite. The life cycle of a rock consists of formation of rock, composition of rock and transformation of rock. The composition of Hornfels and Variolite consists of mineral content and compound content. The mineral content of Hornfels includes Andalusite and mineral content of Variolite includes Olivine, Plagioclase, Pyroxene. You can also check out the list of all Metamorphic Rocks. When we have to compare Hornfels vs Variolite, the texture, color and appearance plays an important role in determining the type of rock. Hornfels is available in brown, dark greenish - grey, green, reddish brown colors whereas, Variolite is available in black, brown, light to dark grey colors. Appearance of Hornfels is Dull and that of Variolite is Dull and Soft. Properties of rock is another aspect for Hornfels vs Variolite. The hardness of Hornfels is 2-3 and that of Variolite is 6. The types of Hornfels are Biotite hornfels whereas types of Variolite are Metamorphic rock. Streak of rock is the color of powder produced when it is dragged across an unweathered surface. The streak of Hornfels is while that of Variolite is white to grey. The specific heat capacity of Hornfels is 0.84 kJ/Kg K and that of Variolite is 0.84 kJ/Kg K. Depending on the properties like hardness, toughness, specific heat capacity, porosity etc., rocks are resistant to heat, wear, impact, etc.Hornfels is heat resistant, impact resistant, pressure resistant whereas Variolite is heat resistant, pressure resistant, wear resistant.