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%
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
Other Categories
Opaque Rock
Coarse Grained Rock, Fine Grained Rock, Medium Grained Rock, Opaque Rock
Color
Black, Blue, Brown, Green, Orange, Red, Tan, Yellow
Black, Brown, Green, Grey, Pink, White
Durability
Durable
Durable
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
-
Curbing
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
Commercial Uses
Creating Artwork, Mirror, Used in aquariums
Cemetery Markers, Commemorative Tablets, Creating Artwork
Types
Fireworks Obsidian, Mahogany, Sheen Obsidian, Snowflake obsidian and Velvet Peacock Obsidian
Igneous rock
Features
Blocks negativity, Helps to protect against depression
Host Rock for Lead
Archaeological Significance
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.
Mineral Content
-
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
Types of Metamorphism
Burial Metamorphism, Cataclastic Metamorphism, Contact Metamorphism
Burial Metamorphism, Cataclastic Metamorphism, Hydrothermal Metamorphism, Impact Metamorphism
Types of Weathering
Biological Weathering, Chemical Weathering, Mechanical Weathering
-
Types of Erosion
Chemical Erosion, Coastal Erosion, Glacier Erosion
-
Grain Size
-
Medium to Fine Coarse Grained
Fracture
Conchoidal
Conchoidal
Porosity
Very Less Porous
Very Less Porous
Luster
Vitreous
Subvitreous to Dull
Specific Gravity
2.6-2.7
2.86
Transparency
Translucent
Translucent
Density
2.6 g/cm3
-9999 g/cm3
Resistance
Heat Resistant, Impact Resistant
Heat Resistant, Wear Resistant
Deposits in Eastern Continents
Asia
Afghanistan, Indonesia, Japan, Russia
Russia
Africa
Kenya
South Africa, Western Africa
Europe
Greece, Hungary, Iceland, Italy, Turkey
-
Deposits in Western Continents
North America
Canada, Mexico, USA
Canada, USA
South America
Argentina, Chile, Ecuador, Peru
-
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, 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.