Obsidian and Foidolite
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
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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