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
Gossan is intensely oxidized, weathered or decomposed rock, usually the upper and exposed part of an ore deposit or mineral vein.
Origin
Ethiopia
Indonesia
Discoverer
Obsius
Cornish Gossen
Etymology
From Latin obsidianus, misprint of Obsianus (lapis) (stone) of Obsius
From Cornish gossen from gos, blood from Old Cornish guit
Class
Igneous Rocks
Metamorphic Rocks
Sub-Class
Durable Rock, Medium Hardness Rock
Durable Rock, Medium Hardness Rock
Other Categories
Opaque Rock
Fine Grained Rock, Medium Grained Rock, Opaque Rock
Texture
Glassy
Rough, Sandy
Color
Black, Blue, Brown, Green, Orange, Red, Tan, Yellow
Brown, Brown- Black, Gold, Green, Rust
Durability
Durable
Durable
Scratch Resistant
Yes
Yes
Appearance
Shiny
Dull and Banded
Interior Uses
Decorative Aggregates, Interior Decoration
Countertops, Decorative Aggregates, Interior Decoration
Exterior Uses
Garden Decoration
As Building Stone, As Facing Stone, Paving Stone, Garden Decoration, Office Buildings
Other Architectural Uses
-
Curbing
Construction Industry
Arrowheads, Cutting Tool, Knives, Scrapers, Spear Points
As Dimension Stone, Cement Manufacture, Construction Aggregate, for Road Aggregate
Medical Industry
Surgery
-
Antiquity Uses
Artifacts, Jewellery
Artifacts
Commercial Uses
Creating Artwork, Mirror, Used in aquariums
Cemetery Markers, Commemorative Tablets, Gemstone
Types
Fireworks Obsidian, Mahogany, Sheen Obsidian, Snowflake obsidian and Velvet Peacock Obsidian
Translocated gossan and Leakage gossan
Features
Blocks negativity, Helps to protect against depression
Clasts are smooth to touch, Easily splits into thin plates
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.
Earth movements can cause rocks to be either deeply buried or squeezed and hence the rocks are heated and put under great pressure.
Mineral Content
-
Apatite, Augite, Biotite, Bronzite, Calcite, Chert, Epidote, Feldspar, Hornblende, Micas, Plagioclase, Pyroxene, Quartz, Sulfides, Zircon
Compound Content
Aluminium Oxide, CaO, Iron(III) Oxide, FeO, Potassium Oxide, MgO, MnO, Sodium Oxide, Phosphorus Pentoxide, Silicon Dioxide, Titanium Dioxide
Aluminium Oxide, CaO, Fe, FeO, Silicon Dioxide, Sulphur
Types of Metamorphism
Burial Metamorphism, Cataclastic Metamorphism, Contact Metamorphism
-
Types of Weathering
Biological Weathering, Chemical Weathering, Mechanical Weathering
-
Types of Erosion
Chemical Erosion, Coastal Erosion, Glacier Erosion
Chemical Erosion, Sea Erosion, Wind Erosion
Grain Size
-
Fine to Medium Grained
Fracture
Conchoidal
Conchoidal
Streak
White
White to Grey
Porosity
Very Less Porous
Highly Porous
Specific Gravity
2.6-2.7
2.0
Transparency
Translucent
Opaque
Density
2.6 g/cm3
-9999 g/cm3
Resistance
Heat Resistant, Impact Resistant
Heat Resistant, Impact Resistant, Pressure Resistant
Deposits in Eastern Continents
Asia
Afghanistan, Indonesia, Japan, Russia
China, India, Indonesia, Russia, Singapore, South Korea
Africa
Kenya
Cape Verde, Ethiopia, Ghana, South Africa, Western Africa
Europe
Greece, Hungary, Iceland, Italy, Turkey
Albania, France, Germany, Great Britain, United Kingdom
Deposits in Western Continents
North America
Canada, Mexico, USA
Canada, USA
South America
Argentina, Chile, Ecuador, Peru
Brazil, Colombia, Ecuador
Deposits in Oceania Continent
Australia
New Zealand
New South Wales, South Australia, Western Australia
All about Obsidian and Gossan Properties
Know all about Obsidian and Gossan properties here. All properties of rocks are important as they define the type of rock and its application. Obsidian belongs to Igneous Rocks while Gossan belongs to Metamorphic Rocks.Texture of Obsidian is Glassy whereas that of Gossan is Rough, Sandy. Obsidian appears Shiny and Gossan appears Dull and Banded. The luster of Obsidian is vitreous while that of Gossan is metallic. Obsidian is available in black, blue, brown, green, orange, red, tan, yellow colors whereas Gossan is available in brown, brown- black, gold, green, rust colors. The commercial uses of Obsidian are creating artwork, mirror, used in aquariums and that of Gossan are cemetery markers, commemorative tablets, gemstone.