Staurolite

Staurolite is a mineral that is composed of iron aluminium silicate. It has a unique cross-like shape.

Because of this, staurolite is sometimes referred to as “fairy stone” or “cross stone”, and is sometimes used in jewellery and other decorative objects.

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Information about Staurolite

 

Appearance

A reddish brown mineral which often occurs in a cruciform twin.

 

Uses and History

 

It is used as an index mineral to help estimate the temperature and pressure under which a rock underwent metamorphism.

Little to no industrial use, sold as specimen pieces and historically popular with Christian missionaries.

 

Locales

Africa:

  • Gorob Mine, Walvis Bay Rural, Erongo Region, Namibia

Asia:

  • Keivy Mountains, Lovozersky District, Murmansk Oblast, Russia

Europe:

  • Fânzeres, Gondomar, Porto, Portugal
  • Nový Malín, Šumperk District, Olomouc Region, Czech Republic
  • Oreshnik, Topolovgrad Municipality, Haskovo Province, Bulgaria
  • Pizzo Forno, Chironico Valley, Faido, Leventina, Ticino, Switzerland
  • Tourch, Quimper, Finistère, Brittany, France

South America:

  • Rubelita, Minas Gerais, Brazil

Antarctica:

Australia and Oceania:

  • Cattle Creek, Rosebud Station, Cloncurry Shire, Queensland, Australia
  • King Island, Tasmania, Australia

North America:

  • Clarendon Township, Frontenac County, Ontario, Canada
  • Diamond Lake locality, Glastonbury, Hartford County, Connecticut, USA
  • Fannin County, Georgia
  • Fairy Stone State Park, Patrick County, Virginia
  • Mora River, Cowles, San Miguel County, New Mexico, USA
  • Pond Hill locality, Lisbon, Grafton County, New Hampshire, USA
  • Windham, Cumberland County, Maine, USA

Mineralogy

Chemistry
Nesosilicite mineral with the chemical formula Fe2+2Al9O6(SiO4)4(O,OH)2
Colours and Variations
Dark brown, brownish-black, red-brown
Streak
White to grey
Luster
Subvitreous, resinous
Transparency
Opaque
Fracture
Sunconchoidal
Crystal habit
Prismatic, typically – often twinned.
Mohs hardness
7.0 – 7.5
Fluorescence
Specific Gravity
3.74 – 3.83
Easiest testing method
Often twinned.

Hazards and Warnings

Mineral collectors should wash their hands after handling specimens, to avoid any exposure to potential toxins.

Almost all rocks, minerals (and, frankly, almost all other substances on earth) can produce toxic dust when cutting, which can cause serious respiratory conditions including silicosis.

When cutting or polishing rocks, minerals, shells, etc, all work should be done wet to minimise the dust, and a suitable respirator or extraction system should be used.

 

Translations

Arabic:

Hindi:

Portuguese:

  • estaurolita

Bengali:

Indonesian:

Punjabi:

English:

Italian:

Russian:

  • ставролит

French:

Japanese:

  • スタウロライト

Spanish:

  • estaurolita

German:

  • Staurolith

Korean:

Thai:

Gujurati:

Mandarin Chinese:

  • 十字石

Urdu:

Further Reading / External Links