Gossan

Pseudotachylite

Gossan and Pseudotachylite

Gossan

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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.

Very fine grained fault rock which is composed of glassy matrix that often contains inclusions of wall-rock fragments.

History

Origin

Indonesia

USA

Discoverer

Cornish Gossen

Unknown

Etymology

From Cornish gossen from gos, blood from Old Cornish guit

From pseudo- +‎ tachylite, a glassy rock generated by frictional heat within faults.

Class

Metamorphic Rocks

Sub-Class

Durable Rock, Medium Hardness Rock

Durable Rock, Hard Rock

Family

Group

Other Categories

Fine Grained Rock, Medium Grained Rock, Opaque Rock

Fine Grained Rock, Opaque Rock

Texture

Rough, Sandy

Quench

Color

Brown, Brown- Black, Gold, Green, Rust

Black, Brown, Green, Grey, Pink, White

Maintenance

Less

Durability

Durable

Water Resistant

✔ ✘

Scratch Resistant

✔ ✘

Stain Resistant

✔ ✘

Wind Resistant

✔ ✘

Acid Resistant

✔ ✘

Appearance

Dull and Banded

Dull and Soft

Uses

Architecture

Interior Uses

Countertops, Decorative Aggregates, Interior Decoration

Decorative Aggregates, Entryways, Interior Decoration

Exterior Uses

As Building Stone, As Facing Stone, Paving Stone, Garden Decoration, Office Buildings

As Building Stone, As Facing Stone, Garden Decoration

Other Architectural Uses

Curbing

Industry

Construction Industry

As Dimension Stone, Cement Manufacture, Construction Aggregate, for Road Aggregate

As Dimension Stone, Cement Manufacture, for Road Aggregate, Making natural cement

Medical Industry

Antiquity Uses

Artifacts

Artifacts, Monuments

Other Uses

Commercial Uses

Cemetery Markers, Commemorative Tablets, Gemstone

Creating Artwork, Gemstone

Types

Translocated gossan and Leakage gossan

Cataclastic rock

Features

Clasts are smooth to touch, Easily splits into thin plates

Host Rock for Lead

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.

Due to change in environmental conditions, rocks are heated and pressurized deep inside the Earth's surface. Pseudotachylite is formed from the extreme heat caused by magma or by the intense collisions and friction of tectonic plates.

Composition

Mineral Content

Apatite, Augite, Biotite, Bronzite, Calcite, Chert, Epidote, Feldspar, Hornblende, Micas, Plagioclase, Pyroxene, Quartz, Sulfides, Zircon

Iron Oxides, Pyroxene, Quartz, Stishovite, Sulfides

Compound Content

Aluminium Oxide, CaO, Fe, FeO, Silicon Dioxide, Sulphur

Carbon Dioxide, Silicon Dioxide, Sulfur Dioxide, Sulphur

Transformation

Metamorphism

✔ ✘

Types of Metamorphism

Burial Metamorphism, Cataclastic Metamorphism, Contact Metamorphism

Weathering

✔ ✘

Types of Weathering

Erosion

✔ ✘

Types of Erosion

Chemical Erosion, Sea Erosion, Wind Erosion

Properties

Physical Properties

Hardness

4-57

1 7

👆🏻

Grain Size

Fine to Medium Grained

Very fine-grained

Fracture

Conchoidal

Uneven

Streak

White to Grey

Light to dark brown

Porosity

Highly Porous

Less Porous

Luster

Metallic

Vitreous

Compressive Strength

-60.00 N/mm²

0.15 450

👆🏻

Cleavage

Toughness

Specific Gravity

2.02.46-2.86

0 8.4

👆🏻

Transparency

Opaque

Transparent to Translucent

Density

-9999 g/cm³2.7-2.9 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

Reserves

Deposits in Eastern Continents

Asia

China, India, Indonesia, Russia, Singapore, South Korea

South Korea

Africa

Cape Verde, Ethiopia, Ghana, South Africa, Western Africa

Western Africa

Europe

Albania, France, Germany, Great Britain, United Kingdom

Great Britain, Switzerland

Others

Deposits in Western Continents

North America

Canada, USA

South America

Brazil, Colombia, Ecuador

Deposits in Oceania Continent

Australia

New South Wales, South Australia, Western Australia

Central Australia, Western Australia

All about Gossan and Pseudotachylite Properties

Know all about Gossan and Pseudotachylite properties here. All properties of rocks are important as they define the type of rock and its application. Gossan and Pseudotachylite belong to Metamorphic Rocks.Texture of Gossan is Rough, Sandy whereas that of Pseudotachylite is Quench. Gossan appears Dull and Banded and Pseudotachylite appears Dull and Soft. The luster of Gossan is metallic while that of Pseudotachylite is vitreous. Gossan is available in brown, brown- black, gold, green, rust colors whereas Pseudotachylite is available in black, brown, green, grey, pink, white colors. The commercial uses of Gossan are cemetery markers, commemorative tablets, gemstone and that of Pseudotachylite are creating artwork, gemstone.