Trona

  • Urao

Trona is a rarely occurring mineral from the mineral class " carbonates and nitrates " (formerly known as carbonates, nitrates and borates, and relatives ). It crystallizes in the monoclinic crystal system with the composition Na3 ( HCO3) (CO3) · 2H2O, is so chemically a hydrous sodium bicarbonate.

Trona usually develops translucent crystals with columnar or fibrous habit, but also massive aggregates of white, gray, yellow and sometimes pink color including all nuances. Even colorless crystals are known.

Special Features

Under UV light Trona may show a greenish to yellowish -green fluorescence.

Trona is water soluble and has an alkaline ( " soap " ) taste. Even in weak acids it is soluble under CO2 tax.

Etymology and history

The name Trona is derived from the Arabic word " Tron ", which is a short name for baking soda ( sodium bicarbonate ). Its root word, however, is even older. He can also be found in the Hebrew נטרן ( natruna ) and in the older Greek word νιτρον ( nitrone ) again, but originally comes from the Egyptian " ntrj " ( = divine ).

First described and named was Trona in 1773 by the Swedish consul in Tripoli Bagge who found the mineral in Fezzan ( Fezzan, Libya ).

The 1759 introduced by Johan Gottschalk Wallerius designation alkali orientale impurum terrestre for a new mineral is indeed associated with the trona from various sources, but corresponds to the chemically similar thermonatrite.

Classification

In the now outdated but still in use 8th edition of the mineral classification by Strunz the Trona " water -containing carbonates without foreign anions " belonged to the common mineral class of " carbonates, nitrates and borates " and then to the Department of where he, along with Baylissit, Chalkonatronit Gaylussite, Pirssonit, soda and thermonatrite formed a distinct group.

The 9th edition used since 2001 and valid by the International Mineralogical Association (IMA ) of the Strunz'schen Mineral classification assigns the Trona in the new class of " carbonates and nitrates " (here, the borates form a separate class). There, the mineral is still one in the department of " Carbonates without additional anions, with H2O" one. However, this is now further divided according to the size of the involved cations and the element group membership of the metals, so that the mineral is found according to its composition in the subsection "With large cations ( alkali and alkaline earth carbonates ) ", where it is the only member the unnamed group 5.CB.15 forms.

The mostly commonly used in English-speaking classification of minerals according to Dana assigns a Trona as the outdated Strunz'sche systematics in the common class of " carbonates, nitrates and borates " and there in the department of " carbonates ". Here he is " 13:01 acids carbonates with different formulas " to find the only member of the unnamed group 13:01:04 within the subdivision of.

Education and Locations

Trona forms in non- oceanic evaporites and is therefore mostly found in salt lakes ( natron ) of many desert areas. He rarely found in the form of efflorescence near escaping gases from fumaroles. Accompanying minerals occur among other Bradleyit, glauberite, halite, mirabilite, natron, Northupit, Pirssonit, Shortite, thermonatrite, thenardite and gypsum in alkaline lakes.

The only known locality in Germany, the slag heaps of lead and silver hut Braubach in Rhineland- Palatinate. In Switzerland, Trona found in the Bex salt mine in the canton of Vaud and in construction work for tunnels for the National Road 9 near Martigny in the canton of Valais.

Other localities lie among others in Argentina, Australia, Bolivia, Chile, China, Greenland, Italy, Canada, Kenya, Libya, Namibia, Russia, South Africa, Sudan, Tanzania, Chad, Czech Republic, Turkey, Uganda, Ukraine, Hungary, Venezuela, the United Kingdom ( UK) and the United States of America (USA).

Crystal structure

Trona crystallizes in the monoclinic space group C2 / c ( Raumgruppen-Nr. 15) with the lattice parameters a = 20.42 Å; b = 3.49 Å; c = 10.33 Å and β = 106.4 °, and four formula units per unit cell.

Use

Trona is a mineral essential for the production of sodium carbonate. In addition to the ammonia - soda process ( the Solvay process ) for the preparation of pure soda ash ( Na2CO3), the Trona process has been in the U.S. since 1952, more and more established. The final ammonia-soda factory by Solvay closed its doors in 1985.

784659
de