Obsidian

Hornfels

Obsidian and Hornfels

Obsidian

Hornfels

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1 Definition

1.1 Definition

Obsidian is a naturally occurring volcanic glass formed as an extrusive igneous rock. It is produced when felsic lava extruded from a volcano cools rapidly with minimum crystal growth

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

Ethiopia

New Zealand

1.2.2 Discoverer

Obsius

Unknown

1.3 Etymology

From Latin obsidianus, misprint of Obsianus (lapis) (stone) of Obsius

From German which means hornstone

1.4 Class

Igneous Rocks

Metamorphic Rocks

1.4.1 Sub-Class

Durable Rock, Medium Hardness Rock

Durable Rock, Soft Rock

1.5 Family

1.5.1 Group

Volcanic

Not Applicable

1.6 Other Categories

Opaque Rock

Fine Grained Rock, Opaque Rock

2 Texture

2.1 Texture

Glassy

Granular, Platy

2.2 Color

Black, Blue, Brown, Green, Orange, Red, Tan, Yellow

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

Shiny

Dull

3 Uses

3.1 Architecture

3.1.1 Interior Uses

Decorative Aggregates, Interior Decoration

Decorative Aggregates, Flooring, Homes, Interior Decoration

3.1.2 Exterior Uses

Garden Decoration

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

3.1.3 Other Architectural Uses

Not Yet Used

Curbing

3.2 Industry

3.2.1 Construction Industry

Arrowheads, Cutting Tool, Knives, Scrapers, Spear Points

for Road Aggregate, Roadstone

3.2.2 Medical Industry

Surgery

Not Yet Used

3.3 Antiquity Uses

Artifacts, Jewellery

Artifacts, Monuments

3.4 Other Uses

3.4.1 Commercial Uses

Creating Artwork, Mirror, Used in aquariums

Cemetery Markers, Commemorative Tablets, Creating Artwork

4 Types

4.1 Types

Fireworks Obsidian, Mahogany, Sheen Obsidian, Snowflake obsidian and Velvet Peacock Obsidian

Biotite hornfels

4.2 Features

Blocks negativity, Helps to protect against depression

Smooth to touch

4.3 Archaeological Significance

4.3.1 Monuments

Not Yet Used

Used

4.3.2 Famous Monuments

Not Applicable

Data Not Available

4.3.3 Sculpture

Not Yet Used

4.3.4 Famous Sculptures

Not Applicable

4.3.5 Pictographs

Used

4.3.6 Petroglyphs

Used

4.3.7 Figurines

Not Yet Used

4.4 Fossils

Absent

5 Formation

5.1 Formation

When the lava is released from volcano, it undergoes a very rapid cooling which freezes the mechanisms of crystallization. The result is a volcanic glass with a uniform smooth texture.

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

Not Available

Andalusite

5.2.2 Compound Content

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

Fe, Mg

5.3 Transformation

5.3.1 Metamorphism

✔ ✘

5.3.2 Types of Metamorphism

Burial Metamorphism, Cataclastic Metamorphism, Contact Metamorphism

Not Applicable

5.3.3 Weathering

✔ ✘

5.3.4 Types of Weathering

Biological Weathering, Chemical Weathering, Mechanical Weathering

Biological Weathering

5.3.5 Erosion

✔ ✘

5.3.6 Types of Erosion

Chemical Erosion, Coastal Erosion, Glacier Erosion

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

6 Properties

6.1 Physical Properties

6.1.1 Hardness

5-5.52-3

1 7

6.1.2 Grain Size

Not Applicable

Fine Grained

6.1.3 Fracture

Conchoidal

6.1.4 Streak

White

Unknown

6.1.5 Porosity

Very Less Porous

Highly Porous

6.1.6 Luster

Vitreous

Shiny

6.1.7 Compressive Strength

0.15 N/mm²5.80 N/mm²

0.15 450

6.1.8 Cleavage

Non-Existent

Perfect

6.1.9 Toughness

Not Available

Not Yet Found

6.1.10 Specific Gravity

2.6-2.73.4-3.9

0 8.4

6.1.11 Transparency

Translucent

Opaque

6.1.12 Density

2.6 g/cm³0.25-0.30 g/cm³

0 1400

1.5 Thermal Properties

1.5.1 Specific Heat Capacity

0.92 kJ/Kg K0.84 kJ/Kg K

0.14 3.2

1.5.2 Resistance

Heat Resistant, Impact Resistant

Heat Resistant, Impact Resistant, Pressure Resistant

2 Reserves

2.1 Deposits in Eastern Continents

2.1.1 Asia

Afghanistan, Indonesia, Japan, Russia

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

3.1.1 Africa

Kenya

Cameroon, East Africa, Tanzania, Western Africa

3.2.1 Europe

Greece, Hungary, Iceland, Italy, Turkey

United Kingdom

3.3.1 Others

Not Yet Found

3.5 Deposits in Western Continents

3.5.1 North America

Canada, Mexico, USA

Canada, USA

3.5.3 South America

Argentina, Chile, Ecuador, Peru

Bolivia, Brazil, Colombia, Ecuador

1.1 Deposits in Oceania Continent

1.2.1 Australia

New Zealand

New South Wales, New Zealand, Queensland, Western Australia

All about Obsidian and Hornfels Properties

Know all about Obsidian and Hornfels properties here. All properties of rocks are important as they define the type of rock and its application. Obsidian belongs to Igneous Rocks while Hornfels belongs to Metamorphic Rocks.Texture of Obsidian is Glassy whereas that of Hornfels is Granular, Platy. Obsidian appears Shiny and Hornfels appears Dull. The luster of Obsidian is vitreous while that of Hornfels is shiny. Obsidian is available in black, blue, brown, green, orange, red, tan, yellow colors whereas Hornfels is available in brown, dark greenish - grey, green, reddish brown colors. The commercial uses of Obsidian are creating artwork, mirror, used in aquariums and that of Hornfels are cemetery markers, commemorative tablets, creating artwork.