Gossan

Tephrite

Gossan and Tephrite

Gossan

Tephrite

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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.

Tephrite is an aphanitic to porphyritic textured, volcanic igneous rock

History

Origin

Indonesia

Germany

Discoverer

Cornish Gossen

Van Tooren

Etymology

From Cornish gossen from gos, blood from Old Cornish guit

From Greek tephra, ashes from Indo-European base, to burn

Class

Metamorphic Rocks

Igneous Rocks

Sub-Class

Durable Rock, Medium Hardness Rock

Durable Rock, Hard Rock

Family

Group

Volcanic

Other Categories

Fine Grained Rock, Medium Grained Rock, Opaque Rock

Coarse Grained Rock, Fine Grained Rock, Medium Grained Rock, Opaque Rock

Texture

Rough, Sandy

Aphanitic to Porphyritic

Color

Brown, Brown- Black, Gold, Green, Rust

Black, Brown, Green, Grey, White

Maintenance

Less

Durability

Durable

Water Resistant

✔ ✘

Scratch Resistant

✔ ✘

Stain Resistant

✔ ✘

Wind Resistant

✔ ✘

Acid Resistant

✔ ✘

Appearance

Dull and Banded

Vesicular

Uses

Architecture

Interior Uses

Countertops, Decorative Aggregates, Interior Decoration

Decorative Aggregates, Flooring, Homes, Interior Decoration

Exterior Uses

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

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

Other Architectural Uses

Curbing

Industry

Construction Industry

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

Landscaping

Medical Industry

Antiquity Uses

Artifacts

Artifacts, Sculpture

Other Uses

Commercial Uses

Cemetery Markers, Commemorative Tablets, Gemstone

Production of Lime, Soil Conditioner

Types

Translocated gossan and Leakage gossan

Igneous 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.

Tephrite is a fine-grained, hard rock which is a type of metasomatite, essentially altered basalt. It forms with or without crystallization, either below the surface as intrusive rocks or on the surface as extrusive rocks.

Composition

Mineral Content

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

Alkali feldspar, Nepheline, Plagioclase, Pyroxene

Compound Content

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

CaO, Carbon Dioxide, MgO, Silicon Dioxide

Transformation

Metamorphism

✔ ✘

Types of Metamorphism

Cataclastic Metamorphism, Contact Metamorphism, Impact Metamorphism, Regional 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, Sea Erosion, Water Erosion

Properties

Physical Properties

Hardness

4-56.5

1 7

👆🏻

Grain Size

Fine to Medium Grained

Medium to Fine Coarse Grained

Fracture

Conchoidal

Uneven

Streak

White to Grey

Bluish Black

Porosity

Highly Porous

Very Less Porous

Luster

Metallic

Subvitreous to Dull

Compressive Strength

-90.00 N/mm²

0.15 450

👆🏻

Cleavage

Crenulation and Pervasive

Toughness

2.4

Specific Gravity

2.02.86

0 8.4

👆🏻

Transparency

Opaque

Density

-9999 g/cm³2.8-2.9 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, Impact Resistant

Reserves

Deposits in Eastern Continents

Asia

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

Africa

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

Namibia, Uganda

Europe

Albania, France, Germany, Great Britain, United Kingdom

Germany, Hungary, Italy, Portugal, Spain

Others

Deposits in Western Continents

North America

Canada, USA

USA

South America

Brazil, Colombia, Ecuador

Deposits in Oceania Continent

Australia

New South Wales, South Australia, Western Australia

New Zealand, Western Australia

All about Gossan and Tephrite Properties

Know all about Gossan and Tephrite properties here. All properties of rocks are important as they define the type of rock and its application. Gossan belongs to Metamorphic Rocks while Tephrite belongs to Igneous Rocks.Texture of Gossan is Rough, Sandy whereas that of Tephrite is Aphanitic to Porphyritic. Gossan appears Dull and Banded and Tephrite appears Vesicular. The luster of Gossan is metallic while that of Tephrite is subvitreous to dull. Gossan is available in brown, brown- black, gold, green, rust colors whereas Tephrite is available in black, brown, green, grey, white colors. The commercial uses of Gossan are cemetery markers, commemorative tablets, gemstone and that of Tephrite are production of lime, soil conditioner.