Oslo’s Opera House and its Marble - Selection and Challenges

Elen Roaldset from the Natural History Museum at the UiO will tell us more about the Oslo's Opera house...

Professor (em.) Elen Roaldset (em. since March 2014).

Before the new Opera House opened in April 2008 the choice and quality of the marble chosen for the roof and indoor floor, had been debated and criticized. The selection of the marble was the result of a thorough process taking into consideration the frames that had been set by the Norwegian parliament (Stortinget in 2002), the architecture and the architects esthetic demands, as well as the EU regulations for pre- and final qualifications of stone manufacturers. Blocks of rocks from the qualified manufacturers were subjected to an extensive rock mechanical and petrological testing by SINTEF. Taking into consideration the test results and the other conditions given, the marble Bianco Carrara La Facciata appeared to be ranked as number one, even when the need for more extensive cleaning became an additional condition.

In late 2007 a yellow to brown discoloration appeared on the indoor marble floor when the overlying protective cover was removed. The stain occurred only on the surfaces of the marble tiles, and could not be seen on edges or fracture surfaces inside the marble. Our investigations showed the stain to contain crystals of native sulphur (S), aphthitalite (K,Na)5Na(SO4)2. During the drying process, the moisture had concentrated the dissolved elements from the marble on the surface of the floor where a change in physical conditions caused weak oxidation of sulfide and precipitation of elementary sulfur, possibly also some other sulfur/chloride compounds, generating the yellow to brown discoloration. Most of the yellow staining disappeared when the marble became dry. The surface staining could be removed by dilute H2O2 .

In early 2013 we were again approached by Statsbygg regarding certain areas on the Opera’s outdoor roof where the marble surface had gained a yellowish to brownish discoloration. This discoloration differed visually from that earlier studied inside. We reported pollution particles and postulated chemical changes due to aging of a protective compound laid on the roof in 2008. Present challenges include to decide the best methods for cleaning and maintenance of marble surfaces in the years to come.


Natural History museum, UiO, Oct. 2014.

Professor (em.) Elen Roaldset (em. since March 2014).

Coworkers: Dr. scient. Andreas Harstad, Associate Professor Rune S. Selbekk, Lab. Eng. Hans Jørgen Berg


Amélie Neuville
Published Aug. 22, 2014 7:07 PM - Last modified Oct. 29, 2014 3:31 PM