Rhyolite

Dacite

Rhyolite and Dacite

Rhyolite

Dacite

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Definition

Rhyolite is a fine-grained igneous rock which is rich in silica

Dacite is a volcanic igneous rock which is rintermediate in composition between andesite and rhyolite

History

Origin

North America

Romania and Moldova, Europe

Discoverer

Ferdinand von Richthofen

Unknown

Etymology

From German Rhyolit, from Greek rhuax lava stream + lithos stone

From Dacia, a province of the Roman Empire which lay between the Danube River and Carpathian Mountains where the rock was first described

Class

Igneous Rocks

Sub-Class

Durable Rock, Hard Rock

Durable Rock, Soft Rock

Family

Group

Volcanic

Other Categories

Coarse Grained Rock, Opaque Rock

Fine Grained Rock, Medium Grained Rock, Opaque Rock

Texture

Aphanitic, Glassy, Porphyritic

Aphanitic to Porphyritic

Color

Grey, White, Light Black

Bluish - Grey, Brown, Grey, Light to Dark Grey

Maintenance

Less

Durability

Durable

Water Resistant

✔ ✘

Scratch Resistant

✔ ✘

Stain Resistant

✔ ✘

Wind Resistant

✔ ✘

Acid Resistant

✔ ✘

Appearance

Banded

Vesicular

Uses

Architecture

Interior Uses

Decorative Aggregates, Homes, Hotels, Interior Decoration, Kitchens

Decorative Aggregates, Entryways, Interior Decoration

Exterior Uses

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

As Building Stone, Paving Stone, Garden Decoration

Other Architectural Uses

Curbing

Industry

Construction Industry

Arrowheads, As Dimension Stone, Building houses or walls, Construction Aggregate, Cutting Tool, for Road Aggregate, Knives

As Dimension Stone, Construction Aggregate, for Road Aggregate, Landscaping

Medical Industry

Antiquity Uses

Artifacts

Other Uses

Commercial Uses

Gemstone, Laboratory bench tops, Jewelry

Commemorative Tablets, Creating Artwork

Types

Pumice Rocks, Obsidian Rocks, Perlite Rocks, Porphyritic Rocks.

Footwall Dacite, Hanging wall Dacite, Tuff and Biotite Dacite

Features

Acidic in nature, Available in lots of colors

Host Rock for Lead, Is one of the oldest rock

Archaeological Significance

Monuments

Famous Monuments

Sculpture

Famous Sculptures

Pictographs

Petroglyphs

Figurines

Fossils

Absent

Formation

Rhyolite is a felsic extrusive rock and due to its high silica content, rhyolite lava is very viscous and is volcanic equivalent of granite.

Dacitic magma is formed by the subduction of young oceanic crust under a thick felsic continental plate. Further, the Oceanic crust is hydrothermally altered as quartz and sodium are added.

Composition

Mineral Content

Biotite, Feldspar, Hornblade, Plagioclase, Pyroxene, Quartz

Amphibole, Apatite, Biotite, Feldspar, Garnet, Hornblade, Magnetite, Plagioclase, Pyroxene, Quartz, Zircon

Compound Content

Ca, Fe, Potassium Oxide, Mg, Potassium, Silicon Dioxide, Sodium

Ca, Fe, Potassium Oxide, Mg, Potassium, Silicon Dioxide

Transformation

Metamorphism

✔ ✘

Types of Metamorphism

Burial Metamorphism, Cataclastic Metamorphism, Regional Metamorphism

Burial Metamorphism, Cataclastic Metamorphism

Weathering

✔ ✘

Types of Weathering

Biological Weathering, Chemical Weathering, Mechanical Weathering

Erosion

✔ ✘

Types of Erosion

Chemical Erosion, Sea Erosion, Water Erosion, Wind Erosion

Chemical Erosion

Properties

Physical Properties

Hardness

6-72-2.25

1 7

👆🏻

Grain Size

Large and Coarse Grained

Medium to Fine Coarse Grained

Fracture

Sub-conchoidal

Conchoidal

Streak

White

Porosity

Highly Porous

Less Porous

Luster

Earthy

Subvitreous to Dull

Compressive Strength

140.00 N/mm²70.00 N/mm²

0.15 450

👆🏻

Cleavage

Perfect

Toughness

Specific Gravity

2.65-2.672.86-2.87

0 8.4

👆🏻

Transparency

Opaque

Translucent

Density

2.4-2.6 g/cm³2.77-2.771 g/cm³

0 1400

👆🏻

Thermal Properties

Specific Heat Capacity

0.71 kJ/Kg K0.92 kJ/Kg K

0.14 3.2

👆🏻

Resistance

Heat Resistant, Wear Resistant

Heat Resistant, Impact Resistant, Pressure Resistant, Wear Resistant

Reserves

Deposits in Eastern Continents

Asia

China, India

Africa

Angola, Egypt, Madagascar, Namibia, Nigeria, South Africa

Europe

Germany, Iceland, Ireland, Italy, Spain

France, Greece, Romania, Scotland, Spain

Others

Deposits in Western Continents

North America

Canada, USA

USA

South America

Argentina, Bolivia, Chile, Colombia, Ecuador, Peru, Venezuela

Deposits in Oceania Continent

Australia

New Zealand, Queensland, Western Australia

New Zealand, South Australia, Western Australia

All about Rhyolite and Dacite Properties

Know all about Rhyolite and Dacite properties here. All properties of rocks are important as they define the type of rock and its application. Rhyolite and Dacite belong to Igneous Rocks.Texture of Rhyolite is Aphanitic, Glassy, Porphyritic whereas that of Dacite is Aphanitic to Porphyritic. Rhyolite appears Banded and Dacite appears Vesicular. The luster of Rhyolite is earthy while that of Dacite is subvitreous to dull. Rhyolite is available in grey, white, light black colors whereas Dacite is available in bluish - grey, brown, grey, light to dark grey colors. The commercial uses of Rhyolite are gemstone, laboratory bench tops, jewelry and that of Dacite are commemorative tablets, creating artwork.