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
Scoria is a dark-colored extrusive igneous rock with abundant round bubble-like cavities
Discoverer
Obsius
Unknown
Etymology
From Latin obsidianus, misprint of Obsianus (lapis) (stone) of Obsius
From late Middle English (denoting slag from molten metal), from Greek skōria refuse, from skōr dung
Class
Igneous Rocks
Igneous Rocks
Sub-Class
Durable Rock, Medium Hardness Rock
Durable Rock, Medium Hardness Rock
Other Categories
Opaque Rock
Fine Grained Rock, Opaque Rock
Color
Black, Blue, Brown, Green, Orange, Red, Tan, Yellow
Black, Brown, Dark Grey to Black, Red
Durability
Durable
Durable
Scratch Resistant
Yes
Yes
Appearance
Shiny
Glassy and Vesicular
Interior Uses
Decorative Aggregates, Interior Decoration
Decorative Aggregates, Interior Decoration
Exterior Uses
Garden Decoration
Garden Decoration, Paving Stone
Other Architectural Uses
-
Curbing
Construction Industry
Arrowheads, Cutting Tool, Knives, Scrapers, Spear Points
Cement Manufacture, Construction Aggregate, for Road Aggregate, In landscaping and drainage works
Medical Industry
Surgery
-
Antiquity Uses
Artifacts, Jewellery
Artifacts, Monuments, Sculpture
Commercial Uses
Creating Artwork, Mirror, Used in aquariums
As a traction material on snow-covered roads, Creating Artwork, High-temperature insulation, In gas barbecue grills
Types
Fireworks Obsidian, Mahogany, Sheen Obsidian, Snowflake obsidian and Velvet Peacock Obsidian
Basaltic Scoria and Andesitic Scoria
Features
Blocks negativity, Helps to protect against depression
Available in Lots of Colors and Patterns, Generally rough to touch, Surfaces are often shiny
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.
Scoria forms when magma containing huge amount of dissolved gas flows from a volcano during an eruption.
Mineral Content
-
Apatite, Biotite, Calcite, Feldspar, Hematite, Hornblade, Ilmenite, Magnetite, Olivine, Pyroxene, Quartz, Silica
Compound Content
Aluminium Oxide, CaO, Iron(III) Oxide, FeO, Potassium Oxide, MgO, MnO, Sodium Oxide, Phosphorus Pentoxide, Silicon Dioxide, Titanium Dioxide
Ca, NaCl
Types of Metamorphism
Burial Metamorphism, Cataclastic Metamorphism, Contact Metamorphism
Burial Metamorphism, Cataclastic Metamorphism, Contact Metamorphism
Types of Weathering
Biological Weathering, Chemical Weathering, Mechanical Weathering
Biological Weathering, Chemical Weathering, Mechanical Weathering
Types of Erosion
Chemical Erosion, Coastal Erosion, Glacier Erosion
Chemical Erosion, Coastal Erosion, Glacier Erosion
Grain Size
-
Fine Grained
Fracture
Conchoidal
Conchoidal
Porosity
Very Less Porous
Highly Porous
Luster
Vitreous
Subvitreous to Dull
Specific Gravity
2.6-2.7
-9999
Transparency
Translucent
Opaque
Density
2.6 g/cm3
-9999 g/cm3
Resistance
Heat Resistant, Impact Resistant
Heat Resistant, Impact Resistant, Pressure Resistant, Wear Resistant
Deposits in Eastern Continents
Asia
Afghanistan, Indonesia, Japan, Russia
Afghanistan, Indonesia, Japan, Russia
Africa
Kenya
Ethiopia, Kenya, Tanzania
Europe
Greece, Hungary, Iceland, Italy, Turkey
Greece, Hungary, Iceland, Italy, Turkey
Deposits in Western Continents
North America
Canada, Mexico, USA
Bahamas, Barbados, Canada, Costa Rica, Cuba, Jamaica, Mexico, USA
South America
Argentina, Chile, Ecuador, Peru
Argentina, Chile, Ecuador, Peru
Deposits in Oceania Continent
Australia
New Zealand
New Zealand, Western Australia
All about Obsidian and Scoria Properties
Know all about Obsidian and Scoria properties here. All properties of rocks are important as they define the type of rock and its application. Obsidian and Scoria belong to Igneous Rocks.Texture of Obsidian is Glassy whereas that of Scoria is Vesicular. Obsidian appears Shiny and Scoria appears Glassy and Vesicular. The luster of Obsidian is vitreous while that of Scoria is subvitreous to dull. Obsidian is available in black, blue, brown, green, orange, red, tan, yellow colors whereas Scoria is available in black, brown, dark grey to black, red colors. The commercial uses of Obsidian are creating artwork, mirror, used in aquariums and that of Scoria are as a traction material on snow-covered roads, creating artwork, high-temperature insulation, in gas barbecue grills.