Chert

Adakite

Chert and Adakite

Chert

Adakite

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Definition

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

Adakite is an intermediate to felsic volcanic rock that has geochemical characteristics of magma which is said to be formed by partial melting of altered basalt that is subducted below volcanic arcs

History

Origin

Adak, Aleutian Islands

Discoverer

Unknown

Defant and Drummond

Etymology

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

From Adak, Aleutian Islands

Class

Sedimentary Rocks

Igneous Rocks

Sub-Class

Durable Rock, Hard Rock

Durable Rock, Medium Hardness Rock

Family

Group

Volcanic

Other Categories

Fine Grained Rock, Opaque Rock

Fine Grained Rock, Medium Grained Rock, Opaque Rock

Texture

Banded, Rough

Porphyritic

Color

Black, Brown, Green, Grey, Red, White

Black, Brown, Light to Dark Grey

Maintenance

Less

Durability

Durable

Water Resistant

✔ ✘

Scratch Resistant

✔ ✘

Stain Resistant

✔ ✘

Wind Resistant

✔ ✘

Acid Resistant

✔ ✘

Appearance

Glassy or Pearly

Dull and Soft

Uses

Architecture

Interior Uses

Decorative Aggregates, Homes

Decorative Aggregates, Floor Tiles, Homes, Hotels, Kitchens

Exterior Uses

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

As Building Stone, As Facing Stone, Office Buildings

Other Architectural Uses

Curbing

Whetstones

Industry

Construction Industry

Arrowheads, Construction Aggregate, Cutting Tool, Spear Points

As Dimension Stone, Cobblestones, Rail Track Ballast, Roadstone

Medical Industry

Antiquity Uses

Artifacts, Monuments

Monuments, Sculpture, Small Figurines

Other Uses

Commercial Uses

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

Commemorative Tablets, Pottery, Used in aquariums

Types

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

Intermediate volcanic rock

Features

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

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

Archaeological Significance

Monuments

Famous Monuments

Sculpture

Famous Sculptures

Pictographs

Petroglyphs

Figurines

Fossils

Present

Absent

Formation

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.

Adakite rocks are formed when the hydrous fluids are released from minerals that break down in metamorphosed basalt, and rise into the mantle they initiate partial melting.

Composition

Mineral Content

Quartz, Silicon

Olivine, Plagioclase, Pyroxene

Compound Content

Silicon Dioxide

Aluminium Oxide, MgO, Silicon Dioxide

Transformation

Metamorphism

✔ ✘

Types of Metamorphism

Cataclastic Metamorphism, Contact Metamorphism, Impact Metamorphism, Regional Metamorphism

Weathering

✔ ✘

Types of Weathering

Chemical Weathering, Mechanical Weathering

Erosion

✔ ✘

Types of Erosion

Chemical Erosion

Coastal Erosion, Sea Erosion, Water Erosion

Properties

Physical Properties

Hardness

6.5-73-4

1 7

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Grain Size

Very fine-grained

Fine to Medium Grained

Fracture

Uneven, Splintery or Conchoidal

Conchoidal

Streak

White

Bluish Black

Porosity

Highly Porous

Less Porous

Luster

Waxy and Dull

Grainy, Pearly and Vitreous

Compressive Strength

450.00 N/mm²200.00 N/mm²

0.15 450

👆🏻

Cleavage

Toughness

1.5

Specific Gravity

2.5-2.8-9999

0 8.4

👆🏻

Transparency

Translucent to Opaque

Opaque

Density

2.7 g/cm³-9999 g/cm³

0 1400

👆🏻

Thermal Properties

Specific Heat Capacity

0.74 kJ/Kg K0.84 kJ/Kg K

0.14 3.2

👆🏻

Resistance

Heat Resistant, Impact Resistant, Pressure Resistant, Wear Resistant

Heat Resistant, Pressure Resistant, Wear Resistant

Reserves

Deposits in Eastern Continents

Asia

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

India, Russia

Africa

Kenya, Morocco, South Africa, Tanzania

Ethiopia, Somalia, South Africa

Europe

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

Iceland

Others

Greenland, Mid-Atlantic Ridge

Deposits in Western Continents

North America

Canada, Mexico, USA

Canada, USA

South America

Bolivia, Brazil

Brazil

Deposits in Oceania Continent

Australia

New South Wales, Queensland, South Australia, Western Australia

All about Chert and Adakite Properties

Know all about Chert and Adakite properties here. All properties of rocks are important as they define the type of rock and its application. Chert belongs to Sedimentary Rocks while Adakite belongs to Igneous Rocks.Texture of Chert is Banded, Rough whereas that of Adakite is Porphyritic. Chert appears Glassy or Pearly and Adakite appears Dull and Soft. The luster of Chert is waxy and dull while that of Adakite is grainy, pearly and vitreous. Chert is available in black, brown, green, grey, red, white colors whereas Adakite is available in black, brown, light to dark grey colors. The commercial uses of Chert are creating artwork, gemstone, in fire-starting tools, jewelry, to ignite fire, used in flintlock firearms and that of Adakite are commemorative tablets, pottery, used in aquariums.