Obsidian

Gneiss

Obsidian and Gneiss

Obsidian

Gneiss

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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

Gneiss is a common and widely distributed type of rock formed by high-grade regional metamorphic processes from pre-existing formations that were originally either igneous or sedimentary rocks

1.2 History

1.2.1 Origin

Ethiopia

Unknown

1.2.2 Discoverer

Obsius

Unknown

1.3 Etymology

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

From the Middle High German verb gneist (to spark; so called because the rock glitters)

1.4 Class

Igneous Rocks

Metamorphic Rocks

1.4.1 Sub-Class

Durable Rock, Medium Hardness Rock

Durable Rock, Hard Rock

1.5 Family

1.5.1 Group

Volcanic

Not Applicable

1.6 Other Categories

Opaque Rock

Coarse Grained Rock, Medium Grained Rock, Opaque Rock

2 Texture

2.1 Texture

Glassy

Banded, Foliated, Platy

2.2 Color

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

Black, Brown, Pink, Red, White

2.3 Maintenance

Less

2.4 Durability

Durable

2.4.1 Water Resistant

✔ ✘

81% Igneous Rocks Rocks have it !

✔ ✘

81% Metamorphic Rocks Rocks have it !

2.4.2 Scratch Resistant

✔ ✘

86% Igneous Rocks Rocks have it !

✔ ✘

65% Metamorphic Rocks Rocks have it !

2.4.3 Stain Resistant

✔ ✘

66% Igneous Rocks Rocks have it !

✔ ✘

42% Metamorphic Rocks Rocks have it !

2.4.4 Wind Resistant

✔ ✘

49% Igneous Rocks Rocks have it !

✔ ✘

19% Metamorphic Rocks Rocks have it !

2.4.5 Acid Resistant

✔ ✘

48% Igneous Rocks Rocks have it !

✔ ✘

15% Metamorphic Rocks Rocks have it !

2.5 Appearance

Shiny

Foliated

3 Uses

3.1 Architecture

3.1.1 Interior Uses

Decorative Aggregates, Interior Decoration

Countertops, Decorative Aggregates, Flooring, Interior Decoration

3.1.2 Exterior Uses

Garden Decoration

As Building Stone, As Facing Stone, Garden Decoration, 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

As Dimension Stone

3.2.2 Medical Industry

Surgery

Not Yet Used

3.3 Antiquity Uses

Artifacts, Jewellery

Artifacts

3.4 Other Uses

3.4.1 Commercial Uses

Creating Artwork, Mirror, Used in aquariums

Cemetery Markers, Jewelry, Tombstones, Used in aquariums

4 Types

4.1 Types

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

Augen Gneiss, Henderson Gneiss, Lewisian Gneiss, Archean and Proterozoic Gneiss.

4.2 Features

Blocks negativity, Helps to protect against depression

Generally rough to touch, Is one of the oldest rock

4.3 Archaeological Significance

4.3.1 Monuments

Not Yet Used

Used

4.3.2 Famous Monuments

Not Applicable

Konark Sun Temple in India, Washington Monument, US

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

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.

Gneiss is a high grade metamorphic rock i.e. it has been subjected to higher temperatures and pressures than schist. It is formed by the metamorphosis of Gneiss forms from volcanic rock, shale or granitie.

5.2 Composition

5.2.1 Mineral Content

Not Available

Biotite, Chlorite, Feldspar, Garnet, Graphite, Hornblade, Micas, Muscovite or Illite, Quartz, Quartzite, Silica, Zircon

5.2.2 Compound Content

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

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

5.3 Transformation

5.3.1 Metamorphism

✔ ✘

97% Igneous Rocks Rocks have it !

✔ ✘

50% Metamorphic Rocks Rocks have it !

5.3.2 Types of Metamorphism

Burial Metamorphism, Cataclastic Metamorphism, Contact Metamorphism

Impact Metamorphism

5.3.3 Weathering

✔ ✘

99% Igneous Rocks Rocks have it !

✔ ✘

65% Metamorphic Rocks Rocks have it !

5.3.4 Types of Weathering

Biological Weathering, Chemical Weathering, Mechanical Weathering

Biological Weathering, Mechanical Weathering

5.3.5 Erosion

✔ ✘

92% Igneous Rocks Rocks have it !

✔ ✘

77% Metamorphic Rocks Rocks have it !

5.3.6 Types of Erosion

Chemical Erosion, Coastal Erosion, Glacier Erosion

Chemical Erosion, Coastal Erosion, Sea Erosion

6 Properties

6.1 Physical Properties

6.1.1 Hardness

5-5.5

6.1.2 Grain Size

Not Applicable

Medium to Coarse Grained

6.1.3 Fracture

Conchoidal

Irregular

6.1.4 Streak

White

6.1.5 Porosity

Very Less Porous

6.1.6 Luster

Vitreous

Dull

6.1.7 Compressive Strength

What Is Flint

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▶

▼

0.15 N/mm²

Rank: 33 (Overall)▶

125.00 N/mm²

Rank: 17 (Overall)▶

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What Is Obsidian

⊕

▶

175 (What Is Grani..)

◀ ▶ ADD ⊕

6.1.8 Cleavage

Non-Existent

Poor

6.1.9 Toughness

Not Available

1.2

6.1.10 Specific Gravity

2.6-2.7

2.5-2.7

6.1.11 Transparency

Translucent

Translucent to Opaque

6.1.12 Density

2.6 g/cm³

2.6-2.9 g/cm³

6.2 Thermal Properties

6.2.1 Specific Heat Capacity

What Is Banded ..

⊕

▶

▼

0.92 kJ/Kg K

Rank: 10 (Overall)▶

Not Available

Rank: N/A (Overall)▶

▲

What Is Granulite

⊕

▶

1.09 (What Is Trave..)

◀ ▶ ADD ⊕

6.2.2 Resistance

Heat Resistant, Impact Resistant

Heat Resistant, Pressure Resistant, Scratch Resistant, Wear Resistant

7 Reserves

7.1 Deposits in Eastern Continents

7.1.1 Asia

Afghanistan, Indonesia, Japan, Russia

China, India, Iran, Iraq, Kazakhstan, Kyrgyzstan, Mongolia, Russia

7.1.2 Africa

Kenya

Cameroon, Ethiopia, Ghana, Kenya, Madagascar, Morocco, Mozambique, Namibia, Nigeria, Tanzania, Togo

7.1.3 Europe

Greece, Hungary, Iceland, Italy, Turkey

Albania, Austria, Bosnia and Herzegovina, Finland, France, Georgia, Germany, Hungary, Italy, Kosovo, Monaco, Norway, Poland, Romania, Serbia, Slovakia, Slovenia, Switzerland, Ukraine, United Kingdom

7.1.4 Others

Not Yet Found

7.2 Deposits in Western Continents

7.2.1 North America

Canada, Mexico, USA

Canada, Costa Rica, Cuba, Mexico, Panama, USA

7.2.2 South America

Argentina, Chile, Ecuador, Peru

Argentina, Bolivia, Brazil, Chile, Colombia, Ecuador, Peru, Venezuela

7.3 Deposits in Oceania Continent

7.3.1 Australia

New Zealand

New South Wales, New Zealand, Queensland, Victoria

All about Obsidian and Gneiss Properties

Know all about Obsidian and Gneiss properties here. All properties of rocks are important as they define the type of rock and its application. Obsidian belongs to Igneous Rocks while Gneiss belongs to Metamorphic Rocks.Texture of Obsidian is Glassy whereas that of Gneiss is Banded, Foliated, Platy. Obsidian appears Shiny and Gneiss appears Foliated. The luster of Obsidian is vitreous while that of Gneiss is dull. Obsidian is available in black, blue, brown, green, orange, red, tan, yellow colors whereas Gneiss is available in black, brown, pink, red, white colors. The commercial uses of Obsidian are creating artwork, mirror, used in aquariums and that of Gneiss are cemetery markers, jewelry, tombstones, used in aquariums.