Obsidian

Gossan

Obsidian and Gossan

Obsidian

Gossan

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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.

History

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

Family

Group

Volcanic

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

Maintenance

Less

Durability

Durable

Water Resistant

✔ ✘

Scratch Resistant

✔ ✘

Stain Resistant

✔ ✘

Wind Resistant

✔ ✘

Acid Resistant

✔ ✘

Appearance

Shiny

Dull and Banded

Uses

Architecture

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

Industry

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

Other Uses

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

Monuments

Famous Monuments

Sculpture

Famous Sculptures

Pictographs

Petroglyphs

Figurines

Fossils

Absent

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.

Composition

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

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, Coastal Erosion, Glacier Erosion

Chemical Erosion, Sea Erosion, Wind Erosion

Properties

Physical Properties

Hardness

5-5.54-5

1 7

👆🏻

Grain Size

Fine to Medium Grained

Fracture

Conchoidal

Streak

White

White to Grey

Porosity

Very Less Porous

Highly Porous

Luster

Vitreous

Metallic

Compressive Strength

0.15 N/mm²-

0.15 450

👆🏻

Cleavage

Toughness

Specific Gravity

2.6-2.72.0

0 8.4

👆🏻

Transparency

Translucent

Opaque

Density

2.6 g/cm³-9999 g/cm³

0 1400

👆🏻

Thermal Properties

Specific Heat Capacity

0.92 kJ/Kg K0.24 kJ/Kg K

0.14 3.2

👆🏻

Resistance

Heat Resistant, Impact Resistant

Heat Resistant, Impact Resistant, Pressure Resistant

Reserves

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

Others

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.