• 责任者：Cai Yuanfeng (State Key Laboratory of Mineral Deposits Research ; Nanjing University ; Nanjing 210093 ; China) ; Li Xiang
• 刊名：Acta Geologica Sinica
• 出版年：2008
• 卷期：82(1)
• 关键词：菱锰矿 ; rhodochrosite ; 赤铁矿 ; hematite ; 石灰岩 ; limestone ; 意大利 ; Italy
• 页码：p.133-138
• 图表：6 illus., 1 table, 11 refs.
• 分类号：0200
• issnNo：ISSN0001-5717
• isbnNo：CN11-1951/P

It has been widely accepted that the color of red sediments results from iron oxides. Thus, the dyeing of hematite is also thought to be reason of reddish limestone in the Cretaceous Ocean Red Beds (CORB). However, as The authors  know that manganese minerals such as rhodochrosite, spessartite, rhodonite and manganocalcite etc., are all red, pink or in varieties of the red. The ESR study showed that the valence of manganese is +2, the content is higher than that of iron cations, and the cations are placed in octahedral sites of the structure. To reveal the origin of the color, three ferric oxides, oolitic hematite, mica hematite and specularite, and a rhodochrosite were selected and measured by a Visible Absorption Spectrometer. The study showed that the peak at 577 nm was stable, well-resolved and the intensity decreased with the decrease of the fractions in spectra of oolitic hematite biphase.