Obsidian

Arkose

Obsidian and Arkose

Obsidian

Arkose

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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

Arkose is a sedimentary rock, specifically a type of sandstone containing at least 25% feldspar

History

Origin

Ethiopia

France

Discoverer

Obsius

Alexandre Brongniart

Etymology

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

From Auvergne region of France used by a French geologist Alexandre Brongniart in 1826 who applied this term to some feldspathic sandstones

Class

Igneous Rocks

Sedimentary Rocks

Sub-Class

Durable Rock, Medium Hardness Rock

Durable Rock, Hard Rock

Family

Group

Volcanic

Other Categories

Opaque Rock

Coarse Grained Rock, Opaque Rock

Texture

Glassy

Clastic

Color

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

Reddish Brown

Maintenance

Less

Durability

Durable

Water Resistant

✔ ✘

Scratch Resistant

✔ ✘

Stain Resistant

✔ ✘

Wind Resistant

✔ ✘

Acid Resistant

✔ ✘

Appearance

Shiny

Rough and Dull

Uses

Architecture

Interior Uses

Decorative Aggregates, Interior Decoration

Decorative Aggregates, Homes, Interior Decoration

Exterior Uses

Garden Decoration

Paving Stone, Office Buildings

Other Architectural Uses

Whetstones

Industry

Construction Industry

Arrowheads, Cutting Tool, Knives, Scrapers, Spear Points

Cement Manufacture, Construction Aggregate, for Road Aggregate, Production of Glass and Ceramics, Raw material for the manufacture of mortar

Medical Industry

Surgery

Antiquity Uses

Artifacts, Jewellery

Artifacts, Sculpture, Small Figurines

Other Uses

Commercial Uses

Creating Artwork, Mirror, Used in aquariums

In aquifers, Soil Conditioner, Source of Magnesia (MgO), Tombstones

Types

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

Arkose

Features

Blocks negativity, Helps to protect against depression

Available in Lots of Colors and Patterns, Generally rough to touch, Is one of the oldest rock

Archaeological Significance

Monuments

Famous Monuments

Sculpture

Famous Sculptures

Pictographs

Petroglyphs

Figurines

Fossils

Absent

Present

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.

Arkose rock forms from the weathering of feldspar-rich igneous or metamorphic rock, most commonly granitic rocks, which are primarily composed of quartz and feldspar.

Composition

Mineral Content

Calcite, Clay, Clay Minerals, Feldspar, Micas, Quartz

Compound Content

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

Aluminium Oxide, CaO, Iron(III) Oxide, Potassium Oxide, MgO, Sodium Oxide, Silicon Dioxide

Transformation

Metamorphism

✔ ✘

Types of Metamorphism

Burial Metamorphism, Cataclastic Metamorphism, Contact Metamorphism

Weathering

✔ ✘

Types of Weathering

Biological Weathering, Chemical Weathering, Mechanical Weathering

Erosion

✔ ✘

Types of Erosion

Chemical Erosion, Coastal Erosion, Glacier Erosion

Coastal Erosion, Glacier Erosion, Water Erosion, Wind Erosion

Properties

Physical Properties

Hardness

5-5.56-7

1 7

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Grain Size

Coarse Grained

Fracture

Conchoidal

Streak

White

Porosity

Very Less Porous

Highly Porous

Luster

Vitreous

Dull

Compressive Strength

0.15 N/mm²80.00 N/mm²

0.15 450

👆🏻

Cleavage

Toughness

Specific Gravity

2.6-2.70

0 8.4

👆🏻

Transparency

Translucent

Opaque

Density

2.6 g/cm³-9999 g/cm³

0 1400

👆🏻

Thermal Properties

Specific Heat Capacity

0.92 kJ/Kg K0.78 kJ/Kg K

0.14 3.2

👆🏻

Resistance

Heat Resistant, Impact Resistant

Heat Resistant, Impact Resistant, Pressure Resistant

Reserves

Deposits in Eastern Continents

Asia

Afghanistan, Indonesia, Japan, Russia

China, India, Kazakhstan, Mongolia, Russia, Uzbekistan

Africa

Kenya

Namibia, Nigeria, South Africa

Europe

Greece, Hungary, Iceland, Italy, Turkey

Austria, Denmark, Germany, Great Britain, Netherlands, Norway, Poland, Sweden, Switzerland, United Kingdom

Others

Greenland

Deposits in Western Continents

North America

Canada, Mexico, USA

Canada, USA

South America

Argentina, Chile, Ecuador, Peru

Brazil

Deposits in Oceania Continent

Australia

New Zealand

New South Wales, New Zealand

All about Obsidian and Arkose Properties

Know all about Obsidian and Arkose properties here. All properties of rocks are important as they define the type of rock and its application. Obsidian belongs to Igneous Rocks while Arkose belongs to Sedimentary Rocks.Texture of Obsidian is Glassy whereas that of Arkose is Clastic. Obsidian appears Shiny and Arkose appears Rough and Dull. The luster of Obsidian is vitreous while that of Arkose is dull. Obsidian is available in black, blue, brown, green, orange, red, tan, yellow colors whereas Arkose is available in reddish brown colors. The commercial uses of Obsidian are creating artwork, mirror, used in aquariums and that of Arkose are in aquifers, soil conditioner, source of magnesia (mgo), tombstones.