Tetragonal Structure (image) Carnegie Institution for Science Share Print E-Mail Caption This is the tetragonal crystal structure of NaFe2As2, courtesy of Alexander Goncharov. Sodium (Na) is represented by the black balls, iron (Fe) by the red balls, and arsenic (As) by the yellow balls. Courtesy of Alexander Goncharov. Credit Alexander Goncharov Usage Restrictions With credit Share Print E-Mail Disclaimer: AAAS and EurekAlert! are not responsible for the accuracy of news releases posted to EurekAlert! by contributing institutions or for the use of any information through the EurekAlert system.