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