Variolite

Chert

Variolite and Chert

Variolite

Chert

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1 Definition

1.1 Definition

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

Chert is a hard, dark, opaque sedimentary rock which is composed of silica with an amorphous fine-grained texture

1.2 History

1.2.1 Origin

France

Unknown

1.2.2 Discoverer

Unknown

1.3 Etymology

From Latin varius, speckled, variegated

From flint-like quartz, 1670s, of unknown origin- a local term, which has been taken into geological use

1.4 Class

Igneous Rocks

Sedimentary Rocks

1.4.1 Sub-Class

Durable Rock, Hard Rock

1.5 Family

1.5.1 Group

Volcanic

Not Applicable

1.6 Other Categories

Opaque Rock

Fine Grained Rock, Opaque Rock

2 Texture

2.1 Texture

Glassy, Massive, Porphyritic, Scoriaceous, Vesicular

Banded, Rough

2.2 Color

Black, Brown, Light to Dark Grey

Black, Brown, Green, Grey, Red, White

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 and Soft

Glassy or Pearly

3 Uses

3.1 Architecture

3.1.1 Interior Uses

Floor Tiles, Flooring, Homes, Hotels, Kitchens

Decorative Aggregates, Homes

3.1.2 Exterior Uses

Garden Decoration, Office Buildings

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

3.1.3 Other Architectural Uses

Curbing

3.2 Industry

3.2.1 Construction Industry

As Dimension Stone, Cobblestones, Rail Track Ballast, Roadstone

Arrowheads, Construction Aggregate, Cutting Tool, Spear Points

3.2.2 Medical Industry

Not Yet Used

3.3 Antiquity Uses

Artifacts, Monuments, Sculpture

Artifacts, Monuments

3.4 Other Uses

3.4.1 Commercial Uses

Cemetery Markers, Creating Artwork

Creating Artwork, Gemstone, In fire-starting tools, Jewelry, To ignite fire, Used in flintlock firearms

4 Types

4.1 Types

Not Available

Flint, Jasper, Radiolarite, Common Chert, Chalcedony, Agate, Onyx, Opal, Magadi-type Chert, Porcelanite, Siliceous Sinter

4.2 Features

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

Clasts are smooth to touch, Easily splits into thin plates, Has High structural resistance against erosion and climate

4.3 Archaeological Significance

4.3.1 Monuments

Used

4.3.2 Famous Monuments

Data Not Available

4.3.3 Sculpture

Used

Not Yet Used

4.3.4 Famous Sculptures

Data Not Available

Not Applicable

4.3.5 Pictographs

Used

Not Used

4.3.6 Petroglyphs

Used

Not Used

4.3.7 Figurines

Used

Not Yet Used

4.4 Fossils

Absent

Present

5 Formation

5.1 Formation

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

Chert forms when microcrystals of silicon dioxide grow within soft sediments that become limestone or chalk. The chert formation can be either of chemical or biological origin.

5.2 Composition

5.2.1 Mineral Content

Olivine, Plagioclase, Pyroxene

Quartz, Silicon

5.2.2 Compound Content

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

Silicon Dioxide

5.3 Transformation

5.3.1 Metamorphism

✔ ✘

5.3.2 Types of Metamorphism

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

Not Applicable

5.3.3 Weathering

✔ ✘

5.3.4 Types of Weathering

Biological Weathering, Chemical Weathering, Mechanical Weathering

Not Applicable

5.3.5 Erosion

✔ ✘

5.3.6 Types of Erosion

Not Applicable

Chemical Erosion

6 Properties

6.1 Physical Properties

6.1.1 Hardness

66.5-7

1 7

6.1.2 Grain Size

Not Applicable

Very fine-grained

6.1.3 Fracture

Conchoidal

Uneven, Splintery or Conchoidal

6.1.4 Streak

White to Grey

White

6.1.5 Porosity

Less Porous

Highly Porous

6.1.6 Luster

Not Available

Waxy and Dull

6.1.7 Compressive Strength

37.50 N/mm²450.00 N/mm²

0.15 450

6.1.8 Cleavage

Not Available

Non-Existent

6.1.9 Toughness

2.3

1.5

6.1.10 Specific Gravity

2.8-32.5-2.8

0 8.4

6.1.11 Transparency

Opaque

Translucent to Opaque

6.1.12 Density

2.9-3.1 g/cm³2.7 g/cm³

0 1400

6.2 Thermal Properties

6.2.1 Specific Heat Capacity

0.84 kJ/Kg K0.74 kJ/Kg K

0.14 3.2

6.2.2 Resistance

Heat Resistant, Pressure Resistant, Wear Resistant

Heat Resistant, Impact Resistant, Pressure Resistant, Wear Resistant

7 Reserves

7.1 Deposits in Eastern Continents

7.1.1 Asia

India, Russia

China, India, Iran, Japan, Oman, Russia, Saudi Arabia, Taiwan, Thailand, Vietnam

7.1.2 Africa

South Africa

Kenya, Morocco, South Africa, Tanzania

7.1.3 Europe

Iceland

Austria, France, Greece, Italy, Malta, Poland, Portugal, Serbia, Spain, Sweden, United Kingdom

7.1.4 Others

Not Yet Found

Greenland, Mid-Atlantic Ridge

7.2 Deposits in Western Continents

7.2.1 North America

Canada, USA

Canada, Mexico, USA

7.2.2 South America

Brazil

Bolivia, Brazil

7.3 Deposits in Oceania Continent

7.3.1 Australia

Not Yet Found

New South Wales, Queensland, South Australia, Western Australia

All about Variolite and Chert Properties

Know all about Variolite and Chert properties here. All properties of rocks are important as they define the type of rock and its application. Variolite belongs to Igneous Rocks while Chert belongs to Sedimentary Rocks.Texture of Variolite is Glassy, Massive, Porphyritic, Scoriaceous, Vesicular whereas that of Chert is Banded, Rough. Variolite appears Dull and Soft and Chert appears Glassy or Pearly. The luster of Variolite is not available while that of Chert is waxy and dull. Variolite is available in black, brown, light to dark grey colors whereas Chert is available in black, brown, green, grey, red, white colors. The commercial uses of Variolite are cemetery markers, creating artwork and that of Chert are creating artwork, gemstone, in fire-starting tools, jewelry, to ignite fire, used in flintlock firearms.