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
  
Vogesite is a porphyritic alkaline igneous rock and is a variety of Lamprophyre which is dominated by essential amphibole, usually hornblende, and potassic feldspar
  
History
  
  
Origin
Ethiopia
  
Unknown
  
Discoverer
Obsius
  
Unknown
  
Etymology
From Latin obsidianus, misprint of Obsianus (lapis) (stone) of Obsius
  
From the variety of Lamprophyre Greek lampros bright and shining + porphureos purple
  
Class
Igneous Rocks
  
Igneous Rocks
  
Sub-Class
Durable Rock, Medium Hardness Rock
  
Durable Rock, Medium Hardness Rock
  
Family
  
  
Group
Volcanic
  
Plutonic
  
Other Categories
Opaque Rock
  
Coarse Grained Rock, Fine Grained Rock, Opaque Rock
  
Texture
Glassy
  
Porphyritic
  
Color
Black, Blue, Brown, Green, Orange, Red, Tan, Yellow
  
Black, Bluish - Grey, Brown, Dark Greenish - Grey, Green, Grey
  
Maintenance
Less
  
Less
  
Durability
Durable
  
Durable
  
Water Resistant
Yes
  
Yes
  
Scratch Resistant
Yes
  
Yes
  
Stain Resistant
No
  
No
  
Wind Resistant
No
  
No
  
Acid Resistant
No
  
Yes
  
Appearance
Shiny
  
Dull, Banded and Foilated
  
Architecture
  
  
Interior Uses
Decorative Aggregates, Interior Decoration
  
Decorative Aggregates, Entryways, Flooring, Homes, Interior Decoration
  
Exterior Uses
Garden Decoration
  
As Building Stone, As Facing Stone, Garden Decoration, Office Buildings, 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, Making natural cement, Manufacture of Magnesium and Dolomite Refractories
  
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
  
An Oil and Gas Reservoir, As a Feed Additive for Livestock, Gemstone, Metallurgical Flux, Production of Lime, Soil Conditioner, Source of Magnesia (MgO)
  
Types
Fireworks Obsidian, Mahogany, Sheen Obsidian, Snowflake obsidian and Velvet Peacock Obsidian
  
Minette, Alnoite, Camptonite, Monchiquite, Fourchite, Vogesite, Appinite and Spessartite
  
Features
Blocks negativity, Helps to protect against depression
  
Always found as volcanic pipes over deep continental crust, Host rock for Diamond, Is one of the oldest rock, Surfaces are often shiny
  
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
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.
  
Vogesite formation takes place deep beneath the Earth’s surface at around 150 to 450 kilometres, and are erupted rapidly and violently.
  
Composition
  
  
Mineral Content
Not Available
  
Amphibole, Carbonate, Garnet, Micas, Olivine, Phlogopite, Pyroxene
  
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, MgO, MnO, Sodium Oxide, Silicon Dioxide, Titanium Dioxide
  
Transformation
  
  
Metamorphism
Yes
  
Yes
  
Types of Metamorphism
Burial Metamorphism, Cataclastic Metamorphism, Contact Metamorphism
  
Burial Metamorphism, Cataclastic Metamorphism, Contact Metamorphism, Hydrothermal Metamorphism, Impact Metamorphism, Regional Metamorphism
  
Weathering
Yes
  
Yes
  
Types of Weathering
Biological Weathering, Chemical Weathering, Mechanical Weathering
  
Biological Weathering, Chemical Weathering, Mechanical Weathering
  
Erosion
Yes
  
Yes
  
Types of Erosion
Chemical Erosion, Coastal Erosion, Glacier Erosion
  
Chemical Erosion, Coastal Erosion, Glacier Erosion, Sea Erosion, Water Erosion, Wind Erosion
  
Physical Properties
  
  
Hardness
5-5.5
  
5-6
  
Grain Size
Not Applicable
  
Fine to Coarse Grained
  
Fracture
Conchoidal
  
Conchoidal
  
Streak
White
  
White
  
Porosity
Very Less Porous
  
Very Less Porous
  
Luster
Vitreous
  
Subvitreous to Dull
  
Compressive Strength
Not Available
  
Cleavage
Non-Existent
  
Conchoidal
  
Toughness
Not Available
  
Not Available
  
Specific Gravity
2.6-2.7
  
2.86-2.87
  
Transparency
Translucent
  
Translucent to Opaque
  
Density
2.6 g/cm3
  
2.95-2.96 g/cm3
  
Thermal Properties
  
  
Specific Heat Capacity
0.92 kJ/Kg K
  
10
Not Available
  
Resistance
Heat Resistant, Impact Resistant
  
Heat Resistant, Impact Resistant
  
Deposits in Eastern Continents
  
  
Asia
Afghanistan, Indonesia, Japan, Russia
  
Russia
  
Africa
Kenya
  
Angola, Botswana, Cameroon, Ethiopia, South Africa
  
Europe
Greece, Hungary, Iceland, Italy, Turkey
  
England, Hungary, Iceland, United Kingdom
  
Others
Not Yet Found
  
Antarctica, Greenland
  
Deposits in Western Continents
  
  
North America
Canada, Mexico, USA
  
Canada, Mexico, USA
  
South America
Argentina, Chile, Ecuador, Peru
  
Argentina, Colombia, Ecuador
  
Deposits in Oceania Continent
  
  
Australia
New Zealand
  
New South Wales, New Zealand, Queensland, South Australia, Western Australia