Chert

Pegmatite

Chert and Pegmatite

Chert

Pegmatite

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Definition

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

Pegmatite rock is a holocrystalline, intrusive igneous rock which is composed of interlocking phaneritic crystals

History

Origin

Discoverer

Unknown

R. J. Hauy

Etymology

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

From Greek pegma, pegmat which means- thing joined together + -ite

Class

Sedimentary Rocks

Igneous Rocks

Sub-Class

Durable Rock, Hard Rock

Family

Group

Plutonic

Other Categories

Fine Grained Rock, Opaque Rock

Coarse Grained Rock, Opaque Rock

Texture

Banded, Rough

Pegmatitic

Color

Black, Brown, Green, Grey, Red, White

Black, Brown, Cream, Green, Grey, Pink, Red, Rust, Silver, White, Yellow

Maintenance

Less

Durability

Durable

Water Resistant

✔ ✘

Scratch Resistant

✔ ✘

Stain Resistant

✔ ✘

Wind Resistant

✔ ✘

Acid Resistant

✔ ✘

Appearance

Glassy or Pearly

Layered, Banded, Veined and Shiny

Uses

Architecture

Interior Uses

Decorative Aggregates, Homes

Decorative Aggregates, Flooring, Interior Decoration

Exterior Uses

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

As Building Stone, As Facing Stone, Paving Stone

Other Architectural Uses

Curbing

Industry

Construction Industry

Arrowheads, Construction Aggregate, Cutting Tool, Spear Points

As Dimension Stone, Building houses or walls, Construction Aggregate, for Road Aggregate, Landscaping

Medical Industry

Antiquity Uses

Artifacts, Monuments

Artifacts, Sculpture, Small Figurines

Other Uses

Commercial Uses

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

Creating Artwork, Jewelry, Source of corundum, tourmalines, beryls and topaz

Types

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

Granite Pegmatite, Gabbro Pegmatite and Diorite Pegmatite

Features

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

Generally rough to touch, Is one of the oldest rock, Source of corundum, tourmalines, beryls and topaz

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.

Pegmatite rock is holocrystalline, intrusive igneous rock which is formed by partial melting and dewatering during the process of metamorphism.

Composition

Mineral Content

Quartz, Silicon

Apatite, Beryl, Feldspar, Fluorite, Garnet, Lepidolite, Quartz, Silica, Spodumene, Topaz

Compound Content

Silicon Dioxide

Aluminium Oxide, CaO, Iron(III) Oxide, FeO, Potassium Oxide, Magnesium Carbonate, MgO, Phosphorus Pentoxide

Transformation

Metamorphism

✔ ✘

Types of Metamorphism

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

Weathering

✔ ✘

Types of Weathering

Biological Weathering, Chemical Weathering, Mechanical Weathering

Erosion

✔ ✘

Types of Erosion

Chemical Erosion

Chemical Erosion, Coastal Erosion, Glacier Erosion, Sea Erosion, Water Erosion, Wind Erosion

Properties

Physical Properties

Hardness

6.5-77

1 7

👆🏻

Grain Size

Very fine-grained

Medium to Coarse Grained

Fracture

Uneven, Splintery or Conchoidal

Conchoidal

Streak

White

Porosity

Highly Porous

Less Porous

Luster

Waxy and Dull

Grainy, Pearly and Vitreous

Compressive Strength

450.00 N/mm²178.54 N/mm²

0.15 450

👆🏻

Cleavage

Perfect

Toughness

1.5

2.1

Specific Gravity

2.5-2.82.6-2.63

0 8.4

👆🏻

Transparency

Translucent to Opaque

Density

2.7 g/cm³2.6-2.65 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, Impact Resistant, Pressure Resistant

Reserves

Deposits in Eastern Continents

Asia

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

China, India, Iran, Japan, Nepal, North Korea, Russia, Saudi Arabia, South Korea

Africa

Kenya, Morocco, South Africa, Tanzania

South Africa

Europe

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

Austria, France, Greece, Ireland, Italy, Netherlands, Slovakia, Spain, Turkey, Ukraine

Others

Greenland, Mid-Atlantic Ridge

Deposits in Western Continents

North America

Canada, Mexico, USA

Canada

South America

Bolivia, Brazil

Brazil

Deposits in Oceania Continent

Australia

New South Wales, Queensland, South Australia, Western Australia

All about Chert and Pegmatite Properties

Know all about Chert and Pegmatite properties here. All properties of rocks are important as they define the type of rock and its application. Chert belongs to Sedimentary Rocks while Pegmatite belongs to Igneous Rocks.Texture of Chert is Banded, Rough whereas that of Pegmatite is Pegmatitic. Chert appears Glassy or Pearly and Pegmatite appears Layered, Banded, Veined and Shiny. The luster of Chert is waxy and dull while that of Pegmatite is grainy, pearly and vitreous. Chert is available in black, brown, green, grey, red, white colors whereas Pegmatite is available in black, brown, cream, green, grey, pink, red, rust, silver, white, yellow 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 Pegmatite are creating artwork, jewelry, source of corundum, tourmalines, beryls and topaz.