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Obsidian and Foidolite


Foidolite and Obsidian


Definition

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   
Foidolite is a rare type of coarse-grained intrusive igneous rock with a feldspathoid mineral content greater than 60%   

History
  
  

Origin
Ethiopia   
Unknown   

Discoverer
Obsius   
Unknown   

Etymology
From Latin obsidianus, misprint of Obsianus (lapis) (stone) of Obsius   
From the mineral feldspathoid which is the main content of rock   

Class
Igneous Rocks   
Igneous Rocks   

Sub-Class
Durable Rock, Medium Hardness Rock   
Durable Rock, Soft Rock   

Family
  
  

Group
Volcanic   
Plutonic   

Other Categories
Opaque Rock   
Coarse Grained Rock, Fine Grained Rock, Medium Grained Rock, Opaque Rock   

Texture

Texture
Glassy   
Earthy   

Color
Black, Blue, Brown, Green, Orange, Red, Tan, Yellow   
Black, Brown, Colourless, Green, Grey, Pink, White   

Maintenance
Less   
Less   

Durability
Durable   
Durable   

Water Resistant
Yes   
No   

Scratch Resistant
Yes   
No   

Stain Resistant
No   
No   

Wind Resistant
No   
No   

Acid Resistant
No   
No   

Appearance
Shiny   
Dull   

Uses

Architecture
  
  

Interior Uses
Decorative Aggregates, Interior Decoration   
Decorative Aggregates, Interior Decoration   

Exterior Uses
Garden Decoration   
As Building Stone, As Facing Stone, Garden Decoration, Paving Stone   

Other Architectural Uses
Not Yet Used   
Curbing   

Industry
  
  

Construction Industry
Arrowheads, Cutting Tool, Knives, Scrapers, Spear Points   
As Dimension Stone, Cement Manufacture, for Road Aggregate   

Medical Industry
Surgery   
Taken as a Supplement for Calcium or Magnesium   

Antiquity Uses
Artifacts, Jewellery   
Artifacts, Monuments, Sculpture   

Other Uses
  
  

Commercial Uses
Creating Artwork, Mirror, Used in aquariums   
Cemetery Markers, Commemorative Tablets, Creating Artwork   

Types

Types
Fireworks Obsidian, Mahogany, Sheen Obsidian, Snowflake obsidian and Velvet Peacock Obsidian   
Not Available   

Features
Blocks negativity, Helps to protect against depression   
Host Rock for Lead   

Archaeological Significance
  
  

Monuments
Not Yet Used   
Used   

Famous Monuments
Not Applicable   
Data Not Available   

Sculpture
Not Yet Used   
Used   

Famous Sculptures
Not Applicable   
Data Not Available   

Pictographs
Used   
Used   

Petroglyphs
Used   
Used   

Figurines
Not Yet Used   
Used   

Fossils
Absent   
Absent   

Formation

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.   
Foidolites is a fine-grained, hard rock which is a type of metasomatite, essentially altered basalt. It forms with or without crystallization, either below the surface as intrusive rocks or on the surface as extrusive rocks.   

Composition
  
  

Mineral Content
Not Available   
Amphibole, Biotite, Feldspar, Olivine, Plagioclase, Pyroxene   

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, FeO   

Transformation
  
  

Metamorphism
Yes   
Yes   

Types of Metamorphism
Burial Metamorphism, Cataclastic Metamorphism, Contact Metamorphism   
Burial Metamorphism, Cataclastic Metamorphism, Hydrothermal Metamorphism, Impact Metamorphism   

Weathering
Yes   
No   

Types of Weathering
Biological Weathering, Chemical Weathering, Mechanical Weathering   
Not Applicable   

Erosion
Yes   
No   

Types of Erosion
Chemical Erosion, Coastal Erosion, Glacier Erosion   
Not Applicable   

Properties

Physical Properties
  
  

Hardness
5-5.5   
1.5   

Grain Size
Not Applicable   
Medium to Fine Coarse Grained   

Fracture
Conchoidal   
Conchoidal   

Streak
White   
White   

Porosity
Very Less Porous   
Very Less Porous   

Luster
Vitreous   
Subvitreous to Dull   

Compressive Strength
0.15 N/mm2   
33
Not Available   

Cleavage
Non-Existent   
Perfect   

Toughness
Not Available   
Not Available   

Specific Gravity
2.6-2.7   
2.86   

Transparency
Translucent   
Translucent   

Density
2.6 g/cm3   
Not Available   

Thermal Properties
  
  

Specific Heat Capacity
0.92 kJ/Kg K   
10
Not Available   

Resistance
Heat Resistant, Impact Resistant   
Heat Resistant, Wear Resistant   

Reserves

Deposits in Eastern Continents
  
  

Asia
Afghanistan, Indonesia, Japan, Russia   
Russia   

Africa
Kenya   
South Africa, Western Africa   

Europe
Greece, Hungary, Iceland, Italy, Turkey   
Not Yet Found   

Others
Not Yet Found   
Not Yet Found   

Deposits in Western Continents
  
  

North America
Canada, Mexico, USA   
Canada, USA   

South America
Argentina, Chile, Ecuador, Peru   
Not Yet Found   

Deposits in Oceania Continent
  
  

Australia
New Zealand   
Central Australia, Western Australia   

Summary >>
<< Reserves

All about Obsidian and Foidolite Properties

Know all about Obsidian and Foidolite properties here. All properties of rocks are important as they define the type of rock and its application. Obsidian and Foidolite belong to Igneous Rocks.Texture of Obsidian is Glassy whereas that of Foidolite is Earthy. Obsidian appears Shiny and Foidolite appears Dull. The luster of Obsidian is vitreous while that of Foidolite is subvitreous to dull. Obsidian is available in black, blue, brown, green, orange, red, tan, yellow colors whereas Foidolite is available in black, brown, colourless, green, grey, pink, white colors. The commercial uses of Obsidian are creating artwork, mirror, used in aquariums and that of Foidolite are cemetery markers, commemorative tablets, creating artwork.

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