Gossan

Obsidian

Gossan and Obsidian

Gossan

Obsidian

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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

History

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

Family

Group

Volcanic

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

Maintenance

Less

Durability

Durable

Water Resistant

✔ ✘

Scratch Resistant

✔ ✘

Stain Resistant

✔ ✘

Wind Resistant

✔ ✘

Acid Resistant

✔ ✘

Appearance

Dull and Banded

Shiny

Uses

Architecture

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

Industry

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

Other Uses

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

Monuments

Famous Monuments

Sculpture

Famous Sculptures

Pictographs

Petroglyphs

Figurines

Fossils

Absent

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.

Composition

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

Transformation

Metamorphism

✔ ✘

Types of Metamorphism

Burial Metamorphism, Cataclastic Metamorphism, Contact Metamorphism

Weathering

✔ ✘

Types of Weathering

Biological Weathering, Chemical Weathering, Mechanical Weathering

Erosion

✔ ✘

Types of Erosion

Chemical Erosion, Sea Erosion, Wind Erosion

Chemical Erosion, Coastal Erosion, Glacier Erosion

Properties

Physical Properties

Hardness

4-55-5.5

1 7

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Grain Size

Fine to Medium Grained

Fracture

Conchoidal

Streak

White to Grey

White

Porosity

Highly Porous

Very Less Porous

Luster

Metallic

Vitreous

Compressive Strength

-0.15 N/mm²

0.15 450

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Cleavage

Toughness

Specific Gravity

2.02.6-2.7

0 8.4

👆🏻

Transparency

Opaque

Translucent

Density

-9999 g/cm³2.6 g/cm³

0 1400

👆🏻

Thermal Properties

Specific Heat Capacity

0.24 kJ/Kg K0.92 kJ/Kg K

0.14 3.2

👆🏻

Resistance

Heat Resistant, Impact Resistant, Pressure Resistant

Heat Resistant, Impact Resistant

Reserves

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

Others

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.