Dacite

Rhyolite

Dacite and Rhyolite

Dacite

Rhyolite

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Definition

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

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

History

Origin

Romania and Moldova, Europe

North America

Discoverer

Unknown

Ferdinand von Richthofen

Etymology

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

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

Class

Igneous Rocks

Sub-Class

Durable Rock, Soft Rock

Durable Rock, Hard Rock

Family

Group

Volcanic

Other Categories

Fine Grained Rock, Medium Grained Rock, Opaque Rock

Coarse Grained Rock, Opaque Rock

Texture

Aphanitic to Porphyritic

Aphanitic, Glassy, Porphyritic

Color

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

Grey, White, Light Black

Maintenance

Less

Durability

Durable

Water Resistant

✔ ✘

Scratch Resistant

✔ ✘

Stain Resistant

✔ ✘

Wind Resistant

✔ ✘

Acid Resistant

✔ ✘

Appearance

Vesicular

Banded

Uses

Architecture

Interior Uses

Decorative Aggregates, Entryways, Interior Decoration

Decorative Aggregates, Homes, Hotels, Interior Decoration, Kitchens

Exterior Uses

As Building Stone, Paving Stone, Garden Decoration

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

Other Architectural Uses

Curbing

Industry

Construction Industry

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

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

Medical Industry

Antiquity Uses

Artifacts

Other Uses

Commercial Uses

Commemorative Tablets, Creating Artwork

Gemstone, Laboratory bench tops, Jewelry

Types

Footwall Dacite, Hanging wall Dacite, Tuff and Biotite Dacite

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

Features

Host Rock for Lead, Is one of the oldest rock

Acidic in nature, Available in lots of colors

Archaeological Significance

Monuments

Famous Monuments

Sculpture

Famous Sculptures

Pictographs

Petroglyphs

Figurines

Fossils

Absent

Formation

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.

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

Composition

Mineral Content

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

Biotite, Feldspar, Hornblade, Plagioclase, Pyroxene, Quartz

Compound Content

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

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

Transformation

Metamorphism

✔ ✘

Types of Metamorphism

Burial Metamorphism, Cataclastic Metamorphism

Burial Metamorphism, Cataclastic Metamorphism, Regional Metamorphism

Weathering

✔ ✘

Types of Weathering

Biological Weathering, Chemical Weathering, Mechanical Weathering

Erosion

✔ ✘

Types of Erosion

Chemical Erosion

Chemical Erosion, Sea Erosion, Water Erosion, Wind Erosion

Properties

Physical Properties

Hardness

2-2.256-7

1 7

👆🏻

Grain Size

Medium to Fine Coarse Grained

Large and Coarse Grained

Fracture

Conchoidal

Sub-conchoidal

Streak

White

Porosity

Less Porous

Highly Porous

Luster

Subvitreous to Dull

Earthy

Compressive Strength

70.00 N/mm²140.00 N/mm²

0.15 450

👆🏻

Cleavage

Perfect

Toughness

Specific Gravity

2.86-2.872.65-2.67

0 8.4

👆🏻

Transparency

Translucent

Opaque

Density

2.77-2.771 g/cm³2.4-2.6 g/cm³

0 1400

👆🏻

Thermal Properties

Specific Heat Capacity

0.92 kJ/Kg K0.71 kJ/Kg K

0.14 3.2

👆🏻

Resistance

Heat Resistant, Impact Resistant, Pressure Resistant, Wear Resistant

Heat Resistant, Wear Resistant

Reserves

Deposits in Eastern Continents

Asia

China, India

Africa

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

Europe

France, Greece, Romania, Scotland, Spain

Germany, Iceland, Ireland, Italy, Spain

Others

Deposits in Western Continents

North America

USA

Canada, USA

South America

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

Deposits in Oceania Continent

Australia

New Zealand, South Australia, Western Australia

New Zealand, Queensland, Western Australia

All about Dacite and Rhyolite Properties

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