Hornfels

Chert

Hornfels and Chert

Hornfels

Chert

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1 Definition

1.1 Definition

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

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

1.2 History

1.2.1 Origin

New Zealand

Unknown

1.2.2 Discoverer

Unknown

1.3 Etymology

From German which means hornstone

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

1.4 Class

Metamorphic Rocks

Sedimentary Rocks

1.4.1 Sub-Class

Durable Rock, Soft Rock

Durable Rock, Hard Rock

1.5 Family

1.5.1 Group

Not Applicable

1.6 Other Categories

Fine Grained Rock, Opaque Rock

2 Texture

2.1 Texture

Granular, Platy

Banded, Rough

2.2 Color

Brown, Dark Greenish - Grey, Green, Reddish Brown

Black, Brown, Green, Grey, Red, White

2.3 Maintenance

Less

2.4 Durability

Durable

2.4.1 Water Resistant

✔ ✘

81% Metamorphic Rocks Rocks have it !

✔ ✘

59% Sedimentary Rocks Rocks have it !

2.4.2 Scratch Resistant

✔ ✘

65% Metamorphic Rocks Rocks have it !

✔ ✘

62% Sedimentary Rocks Rocks have it !

2.4.3 Stain Resistant

✔ ✘

42% Metamorphic Rocks Rocks have it !

✔ ✘

43% Sedimentary Rocks Rocks have it !

2.4.4 Wind Resistant

✔ ✘

19% Metamorphic Rocks Rocks have it !

✔ ✘

38% Sedimentary Rocks Rocks have it !

2.4.5 Acid Resistant

✔ ✘

15% Metamorphic Rocks Rocks have it !

✔ ✘

22% Sedimentary Rocks Rocks have it !

2.5 Appearance

Dull

Glassy or Pearly

3 Uses

3.1 Architecture

3.1.1 Interior Uses

Decorative Aggregates, Flooring, Homes, Interior Decoration

Decorative Aggregates, Homes

3.1.2 Exterior Uses

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

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

3.1.3 Other Architectural Uses

Curbing

3.2 Industry

3.2.1 Construction Industry

for Road Aggregate, Roadstone

Arrowheads, Construction Aggregate, Cutting Tool, Spear Points

3.2.2 Medical Industry

Not Yet Used

3.3 Antiquity Uses

Artifacts, Monuments

3.4 Other Uses

3.4.1 Commercial Uses

Cemetery Markers, Commemorative Tablets, Creating Artwork

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

4 Types

4.1 Types

Biotite hornfels

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

4.2 Features

Smooth to touch

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

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

Used

Not Used

4.3.6 Petroglyphs

Used

Not Used

4.3.7 Figurines

Not Yet Used

4.4 Fossils

Absent

Present

5 Formation

5.1 Formation

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.

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.

5.2 Composition

5.2.1 Mineral Content

Andalusite

Quartz, Silicon

5.2.2 Compound Content

Fe, Mg

Silicon Dioxide

5.3 Transformation

5.3.1 Metamorphism

✔ ✘

50% Metamorphic Rocks Rocks have it !

✔ ✘

19% Sedimentary Rocks Rocks have it !

5.3.2 Types of Metamorphism

Not Applicable

5.3.3 Weathering

✔ ✘

65% Metamorphic Rocks Rocks have it !

✔ ✘

78% Sedimentary Rocks Rocks have it !

5.3.4 Types of Weathering

Biological Weathering

Not Applicable

5.3.5 Erosion

✔ ✘

77% Metamorphic Rocks Rocks have it !

✔ ✘

86% Sedimentary Rocks Rocks have it !

5.3.6 Types of Erosion

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

Chemical Erosion

6 Properties

6.1 Physical Properties

6.1.1 Hardness

2-3

6.5-7

6.1.2 Grain Size

Fine Grained

Very fine-grained

6.1.3 Fracture

Conchoidal

Uneven, Splintery or Conchoidal

6.1.4 Streak

Unknown

White

6.1.5 Porosity

Highly Porous

6.1.6 Luster

Shiny

Waxy and Dull

6.1.7 Compressive Strength

What Is Flint

⊕

▶

▼

5.80 N/mm²

Rank: 31 (Overall)▶

450.00 N/mm²

Rank: 1 (Overall)▶

▲

What Is Obsidian

⊕

▶

175 (What Is Grani..)

◀ ▶ ADD ⊕

6.1.8 Cleavage

Perfect

Non-Existent

6.1.9 Toughness

Not Yet Found

1.5

6.1.10 Specific Gravity

3.4-3.9

2.5-2.8

6.1.11 Transparency

Opaque

Translucent to Opaque

6.1.12 Density

0.25-0.30 g/cm³

2.7 g/cm³

6.2 Thermal Properties

6.2.1 Specific Heat Capacity

What Is Banded ..

⊕

▶

▼

0.84 kJ/Kg K

Rank: 15 (Overall)▶

0.74 kJ/Kg K

Rank: 19 (Overall)▶

▲

What Is Granulite

⊕

▶

1.09 (What Is Trave..)

◀ ▶ ADD ⊕

6.2.2 Resistance

Heat Resistant, Impact Resistant, Pressure Resistant

Heat Resistant, Impact Resistant, Pressure Resistant, Wear Resistant

7 Reserves

7.1 Deposits in Eastern Continents

7.1.1 Asia

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

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

7.1.2 Africa

Cameroon, East Africa, Tanzania, Western Africa

Kenya, Morocco, South Africa, Tanzania

7.1.3 Europe

United Kingdom

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

7.1.4 Others

Not Yet Found

Greenland, Mid-Atlantic Ridge

7.2 Deposits in Western Continents

7.2.1 North America

Canada, USA

Canada, Mexico, USA

7.2.2 South America

Bolivia, Brazil, Colombia, Ecuador

Bolivia, Brazil

7.3 Deposits in Oceania Continent

7.3.1 Australia

New South Wales, New Zealand, Queensland, Western Australia

New South Wales, Queensland, South Australia, Western Australia

All about Hornfels and Chert Properties

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