Ópalo

Características generales


Datos generales


Fórmula: SiO2·nH2O
Sistema de cristalización: Amorfo
Lustre: Vítreo plomizo
Color: Yellow, white, red, brown or blue
Dureza: 5,5-6,5
Rareza: extendido
Características distintivas: Colour play (opalescent), low density, lack of cleavage and crystal faces and fracture filling tendency.

Variedades:


Clasificación

Estado IMA: Válido. Descrito con antelación a 1959 (pre-IMA), se considera un mineral clásico o histórico (grandfathered)

Nickel-Strunz : 04.DA.10
  • 4: Óxidos
  • 04.D: Metal:Oxígeno = 1:2 y similar
  • 04.DA: Con cationes pequeños: Familia de la sílice

Dana 8th ed. : 75.2.1.1

Etimología:

"From the Old Indian upala - ""precious stone.""



Formación y ambiente

Sedimentary and secondary from the alteration of high silica igneous extrusive rocks.

Accessory, extrusive, hydrothermal (low temp), igneous, magmatic (ultra-basic), metamorphic (hydrothermal), secondary, sedimentary, weathering crusts

Propiedades fisicas

Hábito: Stalactitic, reniform, massive or amorphous

Lustre: Vítreo plomizo

Transparencia: Transparente, Opaco

Color: Yellow, white, red, brown or blue

Color en sección fina: Incolora

Raya: Blanco

Dureza (Mohs): 5,5-6,5

Fractura: Concoidal

Densidad: 1,9-2,3 g/cm3 (medida)

Cristalografía

Sistema cristalino: Amorfo

Clase (H-M): 0m () - Indefinida

Propiedades ópticas

Tipo: Isotrópico

Valores RI: nα= 1,43

Dispersión: Ninguna

Propiedades químicas

Fórmula: SiO2·nH2O

Elementos químicos: Si, O, H

Composición química: H2O: 20,66%, H: 3,47%, Si: 32,24%, O: 64,29%,

Tests químicos

Fusibilidad: 7; Mineral tipo: Cuarzo; Punto de fusión: 1710ºC; Infusible con soplete
Reacción a los ácidos: Se disuelve en HF
Formación de sublimados: Infusible.

Otras propiedades

Fluorescente (LW): White
Fluorescente (SW): Greenish yellow
Luminiscente: Yellow-white, yellow-green, white or green
: Green or brown


Relaciones con otros minerales

Minerales acompañantes:

Calcedonia

CalcedoniaÓxidos
Fórmula: SiO2
Dureza: 6.5-7
Color: Incoloro, blanco, gris,...
Raya: Blanco
Brillo: Vítreo
 

Cristobalita

CristobalitaÓxidos
Fórmula: SiO2
Sistema de cristalización: Tetragonal
Dureza: 6-7
Raya: Blanco
Brillo: Vítreo
 

Nontronita

NontronitaSilicatos
Fórmula: Na0.3Fe2((Si,Al)4O10)(OH)2·nH2O
Sistema de cristalización: Monoclínico
Dureza: 1,5-2
Raya: Blanco
Brillo: Terroso
 

Cuarzo

CuarzoÓxidos
Fórmula: SiO2
Sistema de cristalización: Trigonal
Dureza: 7
Color: Blanco, transparente. Según variación también puede ser rosa, rojizo o negro.
Raya: Blanco
Brillo: Vítreo
 

Sepiolita

SepiolitaSilicatos
Fórmula: Mg4(Si6O15)(OH)2·6H2O
Sistema de cristalización: Ortorrómbico
Dureza: 2-2,5
Color: Gris, blanco verde azulado, blanco grisáceo, blanco rojizo, blanco amarillento
Raya: Blanco
Brillo: Terroso
 

Yacimientos y localidades de interés

Localidades

  • White Cliffs, New South Wales, Australia
  • Coober Pedy, South Australia, Australia
  • Cygnet, Tasmania, Australia
  • Proprietary mine, Broken Hill, New South Wales, Australia
  • Prospect Hill, New South Wales, Australia
  • Warranulla, New South wales, Australia
  • Lightning Ridge, New South Wales, Australia
  • White Cliffs, New South Wales, Australia
  • Burra Burra mine, Burra, South Australia, Australia
  • Coober Pedy, South Australia, Australia
  • Cygnet, Tasmania, Australia
  • Proprietary mine, Broken Hill, New South Wales, Australia
  • Prospect Hill, New South Wales, Australia
  • Warranulla, New South wales, Australia
  • Lightning Ridge, New South Wales, Australia
  • Burra Burra mine, Burra, South Australia, Australia
  • White Cliffs, New South Wales, Australia
  • Burra Burra mine, Burra, South Australia, Australia
  • Coober Pedy, South Australia, Australia
  • Cygnet, Tasmania, Australia
  • Proprietary mine, Broken Hill, New South Wales, Australia
  • Prospect Hill, New South Wales, Australia
  • Warranulla, New South wales, Australia
  • Lightning Ridge, New South Wales, Australia
  • White Cliffs, New South Wales, Australia
  • Burra Burra mine, Burra, South Australia, Australia
  • Coober Pedy, South Australia, Australia
  • Cygnet, Tasmania, Australia
  • Proprietary mine, Broken Hill, New South Wales, Australia
  • Prospect Hill, New South Wales, Australia
  • Warranulla, New South wales, Australia
  • Lightning Ridge, New South Wales, Australia
  • Uncía, Bustillo, Potosí Dept, Bolivia
  • Mina Flores mine, Huanuni district, Oruro Dept., Bolivia
  • Corrego do Urucum pegmatite, Minas Gerais, Brazil
  • Poudrette quarry, Mt St.-Hilaire, Rouville Co., Québec, Canada
  • Demix-Varennes quarry, Saint-Amable sill, Varennes, Verchéres Co., Québec, Canada
  • Mt St.-Hilaire, Rouville Co., Québec, Canada
  • Bohouskovice, Jihomoravsky, Czech Republic
  • Gunheath China Clay Pit, Stenalees, St.Austell, Cornwall, England
  • Goonhilly Downs, The Lizard, Cornwall, England
  • Wheal Owles, St. Just, Cornwall, England
  • Wheal Maudlin, Lanlivery, Cornwall, England
  • Wheal Gorland, Gwennap, Cornwall, England
  • Wheal Damsel, Gwennap, Cornwall, England
  • Wheal Carne, St. Just, Cornwall, England
  • Wheal Buller, Redruth, Illogan, Cornwall, England
  • West Carclaze Pit, St.Austell, Cornwall, England
  • Botallack mine, Botallack, St. Just, Cornwall, England
  • Kentmere, Kentmere, Cumbria, England
  • Stennagwyn mine, St. Stephen-in-Brannel, Cornwall, England
  • Stenna Gwyn Mine, St. Austell, Cornwall, England
  • Slip China-stone quarry, St. Dennis, Cornwall, England
  • Rosewarne mine, Gwinear, Cornwall, England
  • Rock China Clay pit, St. Austell, Cornwall, England
  • Gunheath pit, Bugle, Hensbarrow Moor, Cornwall, England
  • Carclase China Clay pit, St. Austell, Cornwall, England
  • Chessy-les-Mines, Rhône, Rhône-Alpes, France
  • Glücksrad mine, Clausthal-Zellerfeld, Harz Mts, Sachsen, Germany
  • Daniel mine, Schneeberg, Sachsen, Germany
  • St. Andreasberg, Hartz Mts, Niedersachsen, Germany
  • Val Graveglia, Liguria, Italy
  • Mount Vesuvius, Naples, Campania, Italy
  • Molinello mine, Val Graveglia, Liguria, Italy
  • Baveno, Lago Maggiore, Piedmont, Italy
  • Cerro de Mercado, Durango, Mexico
  • La Esperanza mine, Durango, Mexico
  • Erongo Mts, Namibia
  • Zabkowice Slaskie, Walbrzych, Poland
  • Mutnovskoe, Kamchatka, Russia
  • Dal'negorsk, Primorskiy Kray, Russia
  • Rodnikovoe, Kamchatka, Russia
  • Polar Urals, Tyumen Oblast, Russia
  • Aldan Shield, Yakutiya, Siberia, Russia
  • Talisker Bay, Isle of Skye, Scotland
  • Pezinok Mine, Malé Karpaty Mts, Slovakia
  • Hotazel mine, Kalahari, Cape Province, South Africa
  • McCormick (Ide Ledge) quarry, East Providence, Providence Co., Rhode Island, USA
  • Rockville, Montgomery Co., Maryland, USA
  • Millington quarry, Millington, Somerset Co., New Jersey, USA
  • Overlook Quarry, Day, Saratoga Co., New York, USA
  • Montclair Quarry, Montclair, Passaic Co., New Jersey, USA
  • New Cornelia Mine, Ajo, Pima Co., Arizona, USA
  • Old Guard Mine, Tombstone, Cochise Co., Arizona, USA
  • Topaz cove, Thomas Range, Juab Co., Utah, USA
  • Midas, Elko Co., Nevada, USA
  • Thomas Range, Juab Co., Utah, USA
  • Magnet Cove, Hot Spring Co., Arkansas, USA
  • Lovejoy Gravel pits, Albany, Carroll Co., New Hampshire, USA
  • Laurel Hill (Snake Hill), Secaucus/Bergen Hill Area, Hudson Co., New Jersey, USA
  • Steamboat Springs, Washoe Co., Nevada, USA
  • San Rafael swell/Temple Rock, Green River, Emery Co., Utah, USA
  • Sedalia Copper Mine, Sedalia, Chaffee Co., Colorado, USA
  • Sneech Pond Copper mine, Cumberland, Providence Co., Rhode Island, USA
  • Tombstone, Cochise Co., Arizona, USA
  • Starrett mines, Warren, Knox Co., Maine, USA
  • Opal Butte, Morrow Co., Oregon, USA
  • The Geysers, Sonoma Co., California, USA
  • Mineral Mts. Area, Milford, Beaver Co., Utah, USA
  • Windslow, Navajo Co., Arizona, USA
  • Watchung Mountain Quarries, Mountainside, Union Co., New Jersey, USA
  • Wah Wah Mountain range, Utah, USA
  • Dunton Quarry etc, Newry Township, Oxford Co., Maine, USA
  • Diamond Hill Granite quarry, Cumberland, Providence Co., Rhode Island, USA
  • King Turquoise mine, Conejos Co., Colorado, USA
  • Jensen Quarry, Riverside Co., California, USA
  • Harris Quarry, Lincoln, Providence Co., Rhode Island, USA
  • Etta Mine (Harney Peak & Pearless), Black Hills, Pennington Co., South Dakota, USA
  • Italian Mt. Area, Aspen, Gunnison Co., Colorado, USA
  • Crestmore Quarry, Crestmore, Riverside Co., California, USA
  • Crawford & Jackford, Crawford Co., Arkansas, USA
  • American mine, Bingham Canyon, Salt Lake Co., Utah, USA
  • Fat Jack mine, Lane Mt., Yavapai Co., Arizona, USA
  • Conklin Limestone Quarry, Lincoln, Providence, Rhode Island, USA
  • Bound Brook Quarry, Bridgewater, Somerset Co., New Jersey, USA
  • Corundum Hill Area, Franklin (Mason Mountain), Macon Co., North Carolina, USA
  • Aggregate Industries quarry, Ashland, Middlesex Co., Massachusetts, USA
  • Conklin quarry, Lincoln, Providence Co., Rhode Island, USA
  • Case Beryl prospects, Portland, Middlesex Co., Connecticut, USA
  • Caverns of Sonora, Edwards Plateau, Sutton Co., Texas, USA
  • Atlantic City iron mine, Fremont Co., Wyoming, USA
  • Great Notch Quarry, Little Falls, Passaic Co., New Jersey, USA
  • Hunting Hill quarry, Rockville, Montgomery Co., Maryland, USA
  • Golconda, Humbolt Co., Nevada, USA
  • Sima Aonda Superior, Auyán-tepuy, Bolivar, Venezuela


Bibliografía y más información

American Mineralogist, vol. 60, p.749, (1975)

Comparte en: