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
Granulite is fine to medium grained metamorphic rock with a granular of polygonal crystals.
Origin
Ethiopia
Central Europe
Discoverer
Obsius
Unknown
Etymology
From Latin obsidianus, misprint of Obsianus (lapis) (stone) of Obsius
From Latin granulum, a little grain or fine grained
Class
Igneous Rocks
Metamorphic Rocks
Sub-Class
Durable Rock, Medium Hardness Rock
Durable Rock, Hard Rock
Group
Volcanic
Not Applicable
Other Categories
Opaque Rock
Coarse Grained Rock, Medium Grained Rock, Opaque Rock
Texture
Glassy
Granoblastic
Color
Black, Blue, Brown, Green, Orange, Red, Tan, Yellow
Black, Brown
Durability
Durable
Durable
Scratch Resistant
Yes
Yes
Appearance
Shiny
Veined or Pebbled
Interior Uses
Decorative Aggregates, Interior Decoration
Bathrooms, Countertops, Decorative Aggregates, Entryways, Flooring, Homes, Hotels, Interior Decoration, Kitchens, Stair Treads
Exterior Uses
Garden Decoration
As Building Stone, As Facing Stone, Garden Decoration, Office Buildings, Paving Stone
Other Architectural Uses
Not Yet Used
Curbing
Construction Industry
Arrowheads, Cutting Tool, Knives, Scrapers, Spear Points
As Dimension Stone, Building houses or walls
Medical Industry
Surgery
Not Yet Used
Antiquity Uses
Artifacts, Jewellery
Artifacts, Monuments, Sculpture
Commercial Uses
Creating Artwork, Mirror, Used in aquariums
Curling, Gemstone, Laboratory bench tops, Soil Conditioner, Tombstones
Types
Fireworks Obsidian, Mahogany, Sheen Obsidian, Snowflake obsidian and Velvet Peacock Obsidian
Not Available
Features
Blocks negativity, Helps to protect against depression
Clasts are smooth to touch
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
Not Used
Petroglyphs
Used
Not Used
Figurines
Not Yet Used
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.
Granulite is a fine-grained granular metamorphic rock in which the main component minerals are feldspars and quartz and forms at high temperature and pressure conditions.
Mineral Content
Not Available
Amphibole, Biotite, Feldspar, Hornblade, Micas, Muscovite or Illite, Plagioclase, 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, Carbon Dioxide, Iron(III) Oxide, FeO, Potassium Oxide, MgO, MnO, Sodium Oxide, Phosphorus Pentoxide, Sulfur Dioxide, Titanium Dioxide
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, Water Erosion, Wind Erosion
Grain Size
Not Applicable
Medium to Coarse Grained
Fracture
Conchoidal
Not Available
Porosity
Very Less Porous
Very Less Porous
Cleavage
Non-Existent
Imperfect
Toughness
Not Available
Not Available
Specific Gravity
2.6-2.7
2.8-3.0
Transparency
Translucent
Opaque
Density
2.6 g/cm3
3.06-3.33 g/cm3
Resistance
Heat Resistant, Impact Resistant
Heat Resistant, Wear Resistant
Deposits in Eastern Continents
Asia
Afghanistan, Indonesia, Japan, Russia
China, India, Iran, Saudi Arabia, Sri Lanka, Taiwan, Thailand, Turkey, Vietnam
Africa
Kenya
Angola, Egypt, Madagascar, Nigeria, South Africa
Europe
Greece, Hungary, Iceland, Italy, Turkey
Austria, Belgium, Finland, France, Germany, Italy, Norway, Sardinia, Spain, Switzerland, The Czech Republic, Venezuela
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
Not Yet Found