Blueschist

Chert

Blueschist and Chert

Blueschist

Chert

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Definition

Blueschist is a metamorphic rock which is generally blue in color and is formed under conditions of high pressure and low temperature

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

History

Origin

USA

Discoverer

Edgar Bailey

Unknown

Etymology

From French schiste, Greek skhistos i.e. split

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

Class

Metamorphic Rocks

Sedimentary Rocks

Sub-Class

Durable Rock, Medium Hardness Rock

Durable Rock, Hard Rock

Family

Group

Other Categories

Fine Grained Rock, Medium Grained Rock, Opaque Rock

Fine Grained Rock, Opaque Rock

Texture

Foliated

Banded, Rough

Color

Blue, Bluish - Grey, Purple, Shades of Blue

Black, Brown, Green, Grey, Red, White

Maintenance

Less

Durability

Durable

Water Resistant

✔ ✘

Scratch Resistant

✔ ✘

Stain Resistant

✔ ✘

Wind Resistant

✔ ✘

Acid Resistant

✔ ✘

Appearance

Dull and Banded

Glassy or Pearly

Uses

Architecture

Interior Uses

Floor Tiles, Flooring, Homes, Hotels, Kitchens

Decorative Aggregates, Homes

Exterior Uses

Garden Decoration, Office Buildings

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

Other Architectural Uses

Curbing

Industry

Construction Industry

As Dimension Stone, Cobblestones, Rail Track Ballast, Roadstone

Arrowheads, Construction Aggregate, Cutting Tool, Spear Points

Medical Industry

Antiquity Uses

Artifacts, Monuments, Sculpture

Artifacts, Monuments

Other Uses

Commercial Uses

Cemetery Markers, Commemorative Tablets, Creating Artwork, Curling, Tombstones

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

Types

Metamorphic rock

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

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

Archaeological Significance

Monuments

Famous Monuments

Sculpture

Famous Sculptures

Pictographs

Petroglyphs

Figurines

Fossils

Absent

Present

Formation

Blueschist forms due to the metamorphism of basalt and other rocks with similar composition at high pressures and low temperatures and approximately corresponding to a depth of 15 to 30 kilometers and 200 to 500 °C.

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.

Composition

Mineral Content

Albite, Chlorite, Epidote, Garnet, Glaucophane, Lawsonite, Muscovite or Illite, Quartz

Quartz, Silicon

Compound Content

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

Silicon Dioxide

Transformation

Metamorphism

✔ ✘

Types of Metamorphism

Weathering

✔ ✘

Types of Weathering

Mechanical Weathering

Erosion

✔ ✘

Types of Erosion

Chemical Erosion, Coastal Erosion, Water Erosion, Wind Erosion

Chemical Erosion

Properties

Physical Properties

Hardness

3.5-46.5-7

1 7

👆🏻

Grain Size

Fine to Medium Grained

Very fine-grained

Fracture

Conchoidal

Uneven, Splintery or Conchoidal

Streak

White to Grey

White

Porosity

Highly Porous

Luster

Dull

Waxy and Dull

Compressive Strength

220.00 N/mm²450.00 N/mm²

0.15 450

👆🏻

Cleavage

Slaty

Toughness

1.5

Specific Gravity

3-3.22.5-2.8

0 8.4

👆🏻

Transparency

Opaque

Translucent to Opaque

Density

2.8-2.9 g/cm³2.7 g/cm³

0 1400

👆🏻

Thermal Properties

Specific Heat Capacity

0.84 kJ/Kg K0.74 kJ/Kg K

0.14 3.2

👆🏻

Resistance

Impact Resistant, Pressure Resistant

Heat Resistant, Impact Resistant, Pressure Resistant, Wear Resistant

Reserves

Deposits in Eastern Continents

Asia

Japan, Turkey

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

Africa

Egypt, Ethiopia, South Africa

Kenya, Morocco, South Africa, Tanzania

Europe

France, Greece, Iceland

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

Others

Greenland, Mid-Atlantic Ridge

Deposits in Western Continents

North America

USA

Canada, Mexico, USA

South America

Bolivia, Brazil

Deposits in Oceania Continent

Australia

New Zealand

New South Wales, Queensland, South Australia, Western Australia

All about Blueschist and Chert Properties

Know all about Blueschist and Chert properties here. All properties of rocks are important as they define the type of rock and its application. Blueschist belongs to Metamorphic Rocks while Chert belongs to Sedimentary Rocks.Texture of Blueschist is Foliated whereas that of Chert is Banded, Rough. Blueschist appears Dull and Banded and Chert appears Glassy or Pearly. The luster of Blueschist is dull while that of Chert is waxy and dull. Blueschist is available in blue, bluish - grey, purple, shades of blue colors whereas Chert is available in black, brown, green, grey, red, white colors. The commercial uses of Blueschist are cemetery markers, commemorative tablets, creating artwork, curling, tombstones and that of Chert are creating artwork, gemstone, in fire-starting tools, jewelry, to ignite fire, used in flintlock firearms.