Chert

Hornfels

Chert and Hornfels

Chert

Hornfels

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1 Definition

1.1 Definition

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

Hornfels is a metamorphic rock formed by the contact between mudstone or other clay rich rock, and a hot igneous body, and represents a heat altered equivalent of the original rock

1.2 History

1.2.1 Origin

Unknown

New Zealand

1.2.2 Discoverer

Unknown

1.3 Etymology

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

From German which means hornstone

1.4 Class

Sedimentary Rocks

Metamorphic Rocks

1.4.1 Sub-Class

Durable Rock, Hard Rock

Durable Rock, Soft Rock

1.5 Family

1.5.1 Group

Not Applicable

1.6 Other Categories

Fine Grained Rock, Opaque Rock

2 Texture

2.1 Texture

Banded, Rough

Granular, Platy

2.2 Color

Black, Brown, Green, Grey, Red, White

Brown, Dark Greenish - Grey, Green, Reddish Brown

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

Glassy or Pearly

Dull

3 Uses

3.1 Architecture

3.1.1 Interior Uses

Decorative Aggregates, Homes

Decorative Aggregates, Flooring, Homes, Interior Decoration

3.1.2 Exterior Uses

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

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

3.1.3 Other Architectural Uses

Curbing

3.2 Industry

3.2.1 Construction Industry

Arrowheads, Construction Aggregate, Cutting Tool, Spear Points

for Road Aggregate, Roadstone

3.2.2 Medical Industry

Not Yet Used

3.3 Antiquity Uses

Artifacts, Monuments

3.4 Other Uses

3.4.1 Commercial Uses

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

Cemetery Markers, Commemorative Tablets, Creating Artwork

4 Types

4.1 Types

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

Biotite hornfels

4.2 Features

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

Smooth to touch

4.3 Archaeological Significance

4.3.1 Monuments

Used

4.3.2 Famous Monuments

Data Not Available

4.3.3 Sculpture

Not Yet Used

4.3.4 Famous Sculptures

Not Applicable

4.3.5 Pictographs

Not Used

Used

4.3.6 Petroglyphs

Not Used

Used

4.3.7 Figurines

Not Yet Used

4.4 Fossils

Present

Absent

5 Formation

5.1 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.

Due to change in environmental conditions, rocks are heated and pressurized deep inside the Earth's surface. Hornfels is formed from the extreme heat caused by magma or by the intense collisions and friction of tectonic plates.

5.2 Composition

5.2.1 Mineral Content

Quartz, Silicon

Andalusite

5.2.2 Compound Content

Silicon Dioxide

Fe, Mg

5.3 Transformation

5.3.1 Metamorphism

✔ ✘

5.3.2 Types of Metamorphism

Not Applicable

5.3.3 Weathering

✔ ✘

5.3.4 Types of Weathering

Not Applicable

Biological Weathering

5.3.5 Erosion

✔ ✘

5.3.6 Types of Erosion

Chemical Erosion

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

6 Properties

6.1 Physical Properties

6.1.1 Hardness

6.5-72-3

1 7

6.1.2 Grain Size

Very fine-grained

Fine Grained

6.1.3 Fracture

Uneven, Splintery or Conchoidal

Conchoidal

6.1.4 Streak

White

Unknown

6.1.5 Porosity

Highly Porous

6.1.6 Luster

Waxy and Dull

Shiny

6.1.7 Compressive Strength

450.00 N/mm²5.80 N/mm²

0.15 450

6.1.8 Cleavage

Non-Existent

Perfect

6.1.9 Toughness

1.5

Not Yet Found

6.1.10 Specific Gravity

2.5-2.83.4-3.9

0 8.4

6.1.11 Transparency

Translucent to Opaque

Opaque

6.1.12 Density

2.7 g/cm³0.25-0.30 g/cm³

0 1400

6.2 Thermal Properties

6.2.1 Specific Heat Capacity

0.74 kJ/Kg K0.84 kJ/Kg K

0.14 3.2

6.2.2 Resistance

Heat Resistant, Impact Resistant, Pressure Resistant, Wear Resistant

Heat Resistant, Impact Resistant, Pressure Resistant

7 Reserves

7.1 Deposits in Eastern Continents

7.1.1 Asia

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

Bangladesh, Bhutan, China, India, North Korea, Qatar, Russia, Saudi Arabia, South Korea, Thailand

7.1.2 Africa

Kenya, Morocco, South Africa, Tanzania

Cameroon, East Africa, Tanzania, Western Africa

7.1.3 Europe

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

United Kingdom

7.1.4 Others

Greenland, Mid-Atlantic Ridge

Not Yet Found

7.2 Deposits in Western Continents

7.2.1 North America

Canada, Mexico, USA

Canada, USA

7.2.2 South America

Bolivia, Brazil

Bolivia, Brazil, Colombia, Ecuador

7.3 Deposits in Oceania Continent

7.3.1 Australia

New South Wales, Queensland, South Australia, Western Australia

New South Wales, New Zealand, Queensland, Western Australia

All about Chert and Hornfels Properties

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