Felsite

Pseudotachylite

Felsite and Pseudotachylite

Felsite

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Definition

Felsite is a very fine grained volcanic rock that may or may not contain larger crystals and light colored rock that typically requires petrographic examination or chemical analysis for more precise definition

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

History

Origin

USA

Discoverer

Unknown

Etymology

From English feldspar and -ite

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

Class

Igneous Rocks

Metamorphic Rocks

Sub-Class

Durable Rock, Medium Hardness Rock

Durable Rock, Hard Rock

Family

Group

Volcanic

Other Categories

Fine Grained Rock, Opaque Rock

Texture

Arborescent Patterned, Vitreous

Quench

Color

Black, Blue, Brown, Green, Orange, Red, Tan, Yellow

Black, Brown, Green, Grey, Pink, White

Maintenance

Less

Durability

Durable

Water Resistant

✔ ✘

Scratch Resistant

✔ ✘

Stain Resistant

✔ ✘

Wind Resistant

✔ ✘

Acid Resistant

✔ ✘

Appearance

Layered, Banded, Veined and Shiny

Dull and Soft

Uses

Architecture

Interior Uses

Decorative Aggregates, Flooring, Interior Decoration

Decorative Aggregates, Entryways, Interior Decoration

Exterior Uses

Paving Stone, Garden Decoration

As Building Stone, As Facing Stone, Garden Decoration

Other Architectural Uses

Curbing

Industry

Construction Industry

Arrowheads, Cutting Tool, Knives, Scrapers, Spear Points

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

Medical Industry

Surgery

Antiquity Uses

Artifacts

Artifacts, Monuments

Other Uses

Commercial Uses

Mirror, Jewelry

Creating Artwork, Gemstone

Types

Igneous rock

Cataclastic rock

Features

Available in Lots of Colors and Patterns, Clasts are smooth to touch, Splintery, Very fine grained rock

Host Rock for Lead

Archaeological Significance

Monuments

Famous Monuments

Sculpture

Famous Sculptures

Pictographs

Petroglyphs

Figurines

Fossils

Absent

Formation

Felsite 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.

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

Feldspar, Iron Oxides

Iron Oxides, Pyroxene, Quartz, Stishovite, Sulfides

Compound Content

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

Carbon Dioxide, Silicon Dioxide, Sulfur Dioxide, Sulphur

Transformation

Metamorphism

✔ ✘

Types of Metamorphism

Burial Metamorphism, Contact Metamorphism, Impact Metamorphism, Regional Metamorphism

Burial Metamorphism, Cataclastic Metamorphism, Contact Metamorphism

Weathering

✔ ✘

Types of Weathering

Biological Weathering, Chemical Weathering, Mechanical Weathering

Erosion

✔ ✘

Types of Erosion

Chemical Erosion, Glacier Erosion, Water Erosion

Properties

Physical Properties

Hardness

5-5.57

1 7

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Grain Size

Fine Grained

Very fine-grained

Fracture

Conchoidal

Uneven

Streak

White

Light to dark brown

Porosity

Very Less Porous

Less Porous

Luster

Vitreous

Compressive Strength

0.15 N/mm²60.00 N/mm²

0.15 450

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Cleavage

Toughness

Specific Gravity

2.6-2.72.46-2.86

0 8.4

👆🏻

Transparency

Translucent

Transparent to Translucent

Density

2.6 g/cm³2.7-2.9 g/cm³

0 1400

👆🏻

Thermal Properties

Specific Heat Capacity

0.92 kJ/Kg K0.92 kJ/Kg K

0.14 3.2

👆🏻

Resistance

Heat Resistant, Impact Resistant

Heat Resistant

Reserves

Deposits in Eastern Continents

Asia

Afghanistan, Indonesia, Japan, Russia

South Korea

Africa

Kenya

Western Africa

Europe

Greece, Hungary, Iceland, Italy, Turkey

Great Britain, Switzerland

Others

Deposits in Western Continents

North America

Canada, Mexico, USA

South America

Argentina, Chile, Ecuador, Peru

Deposits in Oceania Continent

Australia

New Zealand

Central Australia, Western Australia

All about Felsite and Pseudotachylite Properties

Know all about Felsite and Pseudotachylite properties here. All properties of rocks are important as they define the type of rock and its application. Felsite belongs to Igneous Rocks while Pseudotachylite belongs to Metamorphic Rocks.Texture of Felsite is Arborescent Patterned, Vitreous whereas that of Pseudotachylite is Quench. Felsite appears Layered, Banded, Veined and Shiny and Pseudotachylite appears Dull and Soft. The luster of Felsite and Pseudotachylite is vitreous. Felsite is available in black, blue, brown, green, orange, red, tan, yellow colors whereas Pseudotachylite is available in black, brown, green, grey, pink, white colors. The commercial uses of Felsite are mirror, jewelry and that of Pseudotachylite are creating artwork, gemstone.