Argillite

Variolite

Argillite and Variolite

Argillite

Variolite

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Definition

Argillites are highly compact sedimentary or slightly metamorphosed rocks that consist largely or wholly of particles of clay or silt but lack the fissility of shale or the cleavage characteristic of slate

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

France

Discoverer

Unknown

Etymology

From Latin Argilla (clay) and -ite in English which became agrilla+ -ite = Argillite

From Latin varius, speckled, variegated

Class

Sedimentary 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

Clastic, Polished

Glassy, Massive, Porphyritic, Scoriaceous, Vesicular

Color

Dark Grey to Black, Pink, Red, White

Black, Brown, Light to Dark Grey

Maintenance

Less

Durability

Durable

Water Resistant

✔ ✘

Scratch Resistant

✔ ✘

Stain Resistant

✔ ✘

Wind Resistant

✔ ✘

Acid Resistant

✔ ✘

Appearance

Rough and Dull

Dull and Soft

Uses

Architecture

Interior Uses

Decorative Aggregates, Homes, Interior Decoration

Floor Tiles, Flooring, Homes, Hotels, Kitchens

Exterior Uses

As Building Stone, Garden Decoration, Office Buildings

Garden Decoration, Office Buildings

Other Architectural Uses

Curbing, Whetstones

Curbing

Industry

Construction Industry

Used for flooring, stair treads, borders and window sills.

As Dimension Stone, Cobblestones, Rail Track Ballast, Roadstone

Medical Industry

Antiquity Uses

Artifacts, Monuments, Sculpture

Other Uses

Commercial Uses

Fire resistant, Used to manufracture paperweights and bookends

Cemetery Markers, Creating Artwork

Types

Metamorphic rock

Features

Is one of the oldest rock

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

Archaeological Significance

Monuments

Famous Monuments

Sculpture

Famous Sculptures

Pictographs

Petroglyphs

Figurines

Fossils

Present

Absent

Formation

An argillite is a fine-grained sedimentary rock mainly composed of clay particles which forms from lithified muds which contain variable amounts of silt-sized particles.

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

Biotite, Chlorite, Feldspar, Micas, Muscovite or Illite, Plagioclase, Pyrite, Quartz

Olivine, Plagioclase, Pyroxene

Compound Content

Iron(III) Oxide, Potassium Oxide, MgO, Silicon Dioxide

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

Properties

Physical Properties

Hardness

2-36

1 7

👆🏻

Grain Size

Fine Grained

Fracture

Conchoidal to Uneven

Conchoidal

Streak

White to Grey

Porosity

Highly Porous

Less Porous

Luster

Waxy and Dull

Compressive Strength

-37.50 N/mm²

0.15 450

👆🏻

Cleavage

Slaty

Toughness

2.6

2.3

Specific Gravity

2.56-2.682.8-3

0 8.4

👆🏻

Transparency

Opaque

Density

2.54-2.66 g/cm³2.9-3.1 g/cm³

0 1400

👆🏻

Thermal Properties

Specific Heat Capacity

0.87 kJ/Kg K0.84 kJ/Kg K

0.14 3.2

👆🏻

Resistance

Heat Resistant, Impact Resistant

Heat Resistant, Pressure Resistant, Wear Resistant

Reserves

Deposits in Eastern Continents

Asia

Bangladesh, China, India, Russia

India, Russia

Africa

Ethiopia, Kenya, Morocco, South Africa, Tanzania

South Africa

Europe

Austria, France, Germany, Greece, Italy, Romania, Scotland, Spain, Switzerland

Iceland

Others

Deposits in Western Continents

North America

USA

Canada, USA

South America

Bolivia, Chile, Colombia, Ecuador, Peru, Venezuela

Brazil

Deposits in Oceania Continent

Australia

New South Wales, New Zealand, Queensland, Victoria, Western Australia

All about Argillite and Variolite Properties

Know all about Argillite and Variolite properties here. All properties of rocks are important as they define the type of rock and its application. Argillite belongs to Sedimentary Rocks while Variolite belongs to Igneous Rocks.Texture of Argillite is Clastic, Polished whereas that of Variolite is Glassy, Massive, Porphyritic, Scoriaceous, Vesicular. Argillite appears Rough and Dull and Variolite appears Dull and Soft. The luster of Argillite is waxy and dull while that of Variolite is . Argillite is available in dark grey to black, pink, red, white colors whereas Variolite is available in black, brown, light to dark grey colors. The commercial uses of Argillite are fire resistant, used to manufracture paperweights and bookends and that of Variolite are cemetery markers, creating artwork.