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
Greenschist is a metamorphic rock that is formed under lowest temperatures and pressures and is usually produced by regional metamorphism
Discoverer
Obsius
Unknown
Etymology
From Latin obsidianus, misprint of Obsianus (lapis) (stone) of Obsius
From minerals such as chlorite, serpentine, and epidote, and platy minerals such as muscovite and platy serpentine which are green in color
Class
Igneous Rocks
Metamorphic Rocks
Sub-Class
Durable Rock, Medium Hardness Rock
Durable Rock, Medium Hardness Rock
Group
Volcanic
Not Applicable
Other Categories
Opaque Rock
Coarse Grained Rock, Fine Grained Rock, Medium Grained Rock, Opaque Rock
Texture
Glassy
Foliated, Platy
Color
Black, Blue, Brown, Green, Orange, Red, Tan, Yellow
Dark Greenish - Grey, Green
Durability
Durable
Durable
Scratch Resistant
Yes
Yes
Appearance
Shiny
Layered and Shiny
Interior Uses
Decorative Aggregates, Interior Decoration
Bathrooms, Countertops, Decorative Aggregates, Entryways, Homes, Interior Decoration
Exterior Uses
Garden Decoration
As Building Stone, As Facing Stone, Paving Stone, Garden Decoration, Office Buildings
Other Architectural Uses
Not Yet Used
Curbing
Construction Industry
Arrowheads, Cutting Tool, Knives, Scrapers, Spear Points
As Dimension Stone, Building houses or walls, Cement Manufacture, Cutting Tool, for Road Aggregate, Roadstone
Medical Industry
Surgery
Not Yet Used
Antiquity Uses
Artifacts, Jewellery
Artifacts
Commercial Uses
Creating Artwork, Mirror, Used in aquariums
Blackboards, Manufacture of tools, Writing Slates
Types
Fireworks Obsidian, Mahogany, Sheen Obsidian, Snowflake obsidian and Velvet Peacock Obsidian
Not Available
Features
Blocks negativity, Helps to protect against depression
Easily splits into thin plates, Smooth to touch
Archaeological Significance
Monuments
Not Yet Used
Not Yet Used
Famous Monuments
Not Applicable
Not Applicable
Sculpture
Not Yet Used
Not Yet Used
Famous Sculptures
Not Applicable
Not Applicable
Figurines
Not Yet Used
Not Yet Used
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.
Greenschist is medium grade metamorphic rock, formed by the metamorphosis of mudstone or shale, or some types of igneous rock, when it is subjected to higher temperatures and pressures.
Mineral Content
Not Available
Alusite, Amphibole, Biotite, Chlorite, Epidote, Feldspar, Garnet, Graphite, Hornblade, Kyanite, Micas, Muscovite or Illite, Porphyroblasts, Quartz, Serpentine, Sillimanite, Staurolite, Talc
Compound Content
Aluminium Oxide, CaO, Iron(III) Oxide, FeO, Potassium Oxide, MgO, MnO, Sodium Oxide, Phosphorus Pentoxide, Silicon Dioxide, Titanium Dioxide
CaO, Carbon Dioxide, MgO
Types of Metamorphism
Burial Metamorphism, Cataclastic Metamorphism, Contact Metamorphism
Not Applicable
Types of Weathering
Biological Weathering, Chemical Weathering, Mechanical Weathering
Biological Weathering, Chemical Weathering
Types of Erosion
Chemical Erosion, Coastal Erosion, Glacier Erosion
Chemical Erosion, Coastal Erosion, Glacier Erosion, Sea Erosion
Grain Size
Not Applicable
Medium to Fine Coarse Grained
Fracture
Conchoidal
Conchoidal
Porosity
Very Less Porous
Highly Porous
Compressive Strength
Not Available
Cleavage
Non-Existent
Slaty
Toughness
Not Available
1.5
Specific Gravity
2.6-2.7
2.5-2.9
Transparency
Translucent
Opaque
Density
2.6 g/cm3
2.8-2.9 g/cm3
Specific Heat Capacity
Not Available
Resistance
Heat Resistant, Impact Resistant
Impact Resistant, Pressure Resistant, Water Resistant
Deposits in Eastern Continents
Asia
Afghanistan, Indonesia, Japan, Russia
Afghanistan, Bangladesh, Bhutan, China, India, Japan, Kazakhstan, Malaysia, Pakistan, Russia, Thailand, Turkey, Vietnam
Africa
Kenya
Egypt, Ethiopia, Morocco, Nigeria, South Africa
Europe
Greece, Hungary, Iceland, Italy, Turkey
Austria, England, France, Georgia, Germany, Italy, Liechtenstein, Monaco, Norway, Slovenia, Spain, Sweden, Switzerland
Others
Not Yet Found
Not Yet Found
Deposits in Western Continents
North America
Canada, Mexico, USA
Canada, Costa Rica, Cuba, Mexico, Panama, USA
South America
Argentina, Chile, Ecuador, Peru
Brazil, Colombia, Guyana
Deposits in Oceania Continent
Australia
New Zealand
New South Wales, New Zealand, Queensland