Chert

Foidolite

Chert and Foidolite

Chert

Foidolite

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Definition

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

Foidolite is a rare type of coarse-grained intrusive igneous rock with a feldspathoid mineral content greater than 60%

History

Origin

Discoverer

Unknown

Etymology

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

From the mineral feldspathoid which is the main content of rock

Class

Sedimentary Rocks

Igneous Rocks

Sub-Class

Durable Rock, Hard Rock

Durable Rock, Soft Rock

Family

Group

Plutonic

Other Categories

Fine Grained Rock, Opaque Rock

Coarse Grained Rock, Fine Grained Rock, Medium Grained Rock, Opaque Rock

Texture

Banded, Rough

Earthy

Color

Black, Brown, Green, Grey, Red, White

Black, Brown, Green, Grey, Pink, White

Maintenance

Less

Durability

Durable

Water Resistant

✔ ✘

Scratch Resistant

✔ ✘

Stain Resistant

✔ ✘

Wind Resistant

✔ ✘

Acid Resistant

✔ ✘

Appearance

Glassy or Pearly

Dull

Uses

Architecture

Interior Uses

Decorative Aggregates, Homes

Decorative Aggregates, Interior Decoration

Exterior Uses

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

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

Other Architectural Uses

Curbing

Industry

Construction Industry

Arrowheads, Construction Aggregate, Cutting Tool, Spear Points

As Dimension Stone, Cement Manufacture, for Road Aggregate

Medical Industry

Taken as a Supplement for Calcium or Magnesium

Antiquity Uses

Artifacts, Monuments

Artifacts, Monuments, Sculpture

Other Uses

Commercial Uses

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

Cemetery Markers, Commemorative Tablets, Creating Artwork

Types

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

Igneous rock

Features

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

Host Rock for Lead

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.

Foidolites is a fine-grained, hard rock which is a type of metasomatite, essentially altered basalt. It forms with or without crystallization, either below the surface as intrusive rocks or on the surface as extrusive rocks.

Composition

Mineral Content

Quartz, Silicon

Amphibole, Biotite, Feldspar, Olivine, Plagioclase, Pyroxene

Compound Content

Silicon Dioxide

Aluminium Oxide, CaO, Iron(III) Oxide, FeO

Transformation

Metamorphism

✔ ✘

Types of Metamorphism

Burial Metamorphism, Cataclastic Metamorphism, Hydrothermal Metamorphism, Impact Metamorphism

Weathering

✔ ✘

Types of Weathering

Erosion

✔ ✘

Types of Erosion

Chemical Erosion

Properties

Physical Properties

Hardness

6.5-71.5

1 7

👆🏻

Grain Size

Very fine-grained

Medium to Fine Coarse Grained

Fracture

Uneven, Splintery or Conchoidal

Conchoidal

Streak

White

Porosity

Highly Porous

Very Less Porous

Luster

Waxy and Dull

Subvitreous to Dull

Compressive Strength

450.00 N/mm²80.00 N/mm²

0.15 450

👆🏻

Cleavage

Perfect

Toughness

1.5

Specific Gravity

2.5-2.82.86

0 8.4

👆🏻

Transparency

Translucent to Opaque

Translucent

Density

2.7 g/cm³-9999 g/cm³

0 1400

👆🏻

Thermal Properties

Specific Heat Capacity

0.74 kJ/Kg K0.79 kJ/Kg K

0.14 3.2

👆🏻

Resistance

Heat Resistant, Impact Resistant, Pressure Resistant, Wear Resistant

Heat Resistant, Wear Resistant

Reserves

Deposits in Eastern Continents

Asia

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

Russia

Africa

Kenya, Morocco, South Africa, Tanzania

South Africa, Western Africa

Europe

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

Others

Greenland, Mid-Atlantic Ridge

Deposits in Western Continents

North America

Canada, Mexico, USA

Canada, USA

South America

Bolivia, Brazil

Deposits in Oceania Continent

Australia

New South Wales, Queensland, South Australia, Western Australia

Central Australia, Western Australia

All about Chert and Foidolite Properties

Know all about Chert and Foidolite properties here. All properties of rocks are important as they define the type of rock and its application. Chert belongs to Sedimentary Rocks while Foidolite belongs to Igneous Rocks.Texture of Chert is Banded, Rough whereas that of Foidolite is Earthy. Chert appears Glassy or Pearly and Foidolite appears Dull. The luster of Chert is waxy and dull while that of Foidolite is subvitreous to dull. Chert is available in black, brown, green, grey, red, white colors whereas Foidolite is available in black, brown, green, grey, pink, white 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 Foidolite are cemetery markers, commemorative tablets, creating artwork.