Variolite

Tephrite

Variolite and Tephrite

Variolite

Tephrite

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Definition

Variolites are a group of dark green basic igneous rocks which exhibit pale colored spots, or spherules, especially on weathered surfaces, that give them a pockmarked appearance

Tephrite is an aphanitic to porphyritic textured, volcanic igneous rock

History

Origin

France

Germany

Discoverer

Unknown

Van Tooren

Etymology

From Latin varius, speckled, variegated

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

Class

Igneous Rocks

Sub-Class

Durable Rock, Hard Rock

Family

Group

Volcanic

Other Categories

Opaque Rock

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

Texture

Glassy, Massive, Porphyritic, Scoriaceous, Vesicular

Aphanitic to Porphyritic

Color

Black, Brown, Light to Dark Grey

Black, Brown, Green, Grey, White

Maintenance

Less

Durability

Durable

Water Resistant

✔ ✘

Scratch Resistant

✔ ✘

Stain Resistant

✔ ✘

Wind Resistant

✔ ✘

Acid Resistant

✔ ✘

Appearance

Dull and Soft

Vesicular

Uses

Architecture

Interior Uses

Floor Tiles, Flooring, Homes, Hotels, Kitchens

Decorative Aggregates, Flooring, Homes, Interior Decoration

Exterior Uses

Garden Decoration, Office Buildings

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

Other Architectural Uses

Curbing

Industry

Construction Industry

As Dimension Stone, Cobblestones, Rail Track Ballast, Roadstone

Landscaping

Medical Industry

Antiquity Uses

Artifacts, Monuments, Sculpture

Artifacts, Sculpture

Other Uses

Commercial Uses

Cemetery Markers, Creating Artwork

Production of Lime, Soil Conditioner

Types

Metamorphic rock

Igneous rock

Features

Has High structural resistance against erosion and climate, Very fine grained rock

Host Rock for Lead

Archaeological Significance

Monuments

Famous Monuments

Sculpture

Famous Sculptures

Pictographs

Petroglyphs

Figurines

Fossils

Absent

Formation

Variolites are a group of dark green basic igneous rocks that exhibit pale colored spots on weathered surfaces that give them a pockmarked appearance.

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

Olivine, Plagioclase, Pyroxene

Alkali feldspar, Nepheline, Plagioclase, Pyroxene

Compound Content

Aluminium Oxide, CaO, Iron(III) Oxide, FeO, Potassium Oxide, MgO, MnO, Sodium Oxide, Phosphorus Pentoxide, Silicon Dioxide, Titanium Dioxide

CaO, Carbon Dioxide, MgO, Silicon Dioxide

Transformation

Metamorphism

✔ ✘

Types of Metamorphism

Burial Metamorphism, Cataclastic Metamorphism, Contact Metamorphism, Hydrothermal Metamorphism, Impact Metamorphism, Regional 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, Coastal Erosion, Glacier Erosion, Sea Erosion, Water Erosion

Properties

Physical Properties

Hardness

66.5

1 7

👆🏻

Grain Size

Medium to Fine Coarse Grained

Fracture

Conchoidal

Uneven

Streak

White to Grey

Bluish Black

Porosity

Less Porous

Very Less Porous

Luster

Subvitreous to Dull

Compressive Strength

37.50 N/mm²90.00 N/mm²

0.15 450

👆🏻

Cleavage

Crenulation and Pervasive

Toughness

2.3

2.4

Specific Gravity

2.8-32.86

0 8.4

👆🏻

Transparency

Opaque

Density

2.9-3.1 g/cm³2.8-2.9 g/cm³

0 1400

👆🏻

Thermal Properties

Specific Heat Capacity

0.84 kJ/Kg K0.92 kJ/Kg K

0.14 3.2

👆🏻

Resistance

Heat Resistant, Pressure Resistant, Wear Resistant

Heat Resistant, Impact Resistant

Reserves

Deposits in Eastern Continents

Asia

India, Russia

Africa

South Africa

Namibia, Uganda

Europe

Iceland

Germany, Hungary, Italy, Portugal, Spain

Others

Deposits in Western Continents

North America

Canada, USA

USA

South America

Brazil

Deposits in Oceania Continent

Australia

New Zealand, Western Australia

All about Variolite and Tephrite Properties

Know all about Variolite and Tephrite properties here. All properties of rocks are important as they define the type of rock and its application. Variolite and Tephrite belong to Igneous Rocks.Texture of Variolite is Glassy, Massive, Porphyritic, Scoriaceous, Vesicular whereas that of Tephrite is Aphanitic to Porphyritic. Variolite appears Dull and Soft and Tephrite appears Vesicular. The luster of Variolite is while that of Tephrite is subvitreous to dull. Variolite is available in black, brown, light to dark grey colors whereas Tephrite is available in black, brown, green, grey, white colors. The commercial uses of Variolite are cemetery markers, creating artwork and that of Tephrite are production of lime, soil conditioner.