Diatomite deposit in the basin of Lake Soijärvi, central Finland

Abstract

Diatomite and underlying diatomaceous gyttja are met with in the overgrown Soijärvi basin at Karttula. Diatomite is considered a material containing abundant diatoms and with a SiO2 content of 60 %; diatomaceous gyttja has a SiO2 content of 20—60 The diatom stratigraphy of the Soijärvi sequence was studied. The diatomite and the diatomaceous gyttja are dominated by the comparatively small Centrales diatoms, mainly Melosira distans and variations. The diatom flora encountered was on the whole very broken. The chemical composition, porosity and melting temperature were determined on diatomite in a natural state. Porosity was also determined after ingnition at 700°C. The distribution in particle size was determined on diatomite treated with hydrogen peroxide. The specific surface area of the diatomite in a natural state is 20,100 m2/kg and, when ignited, 28,800 m2/kg.

Keywords

• diatomite
• diatomaceous gyttja
• diatom stratigraphy
• particle size distribution
• specific surface area
• porosity
• chemical composition
• melting temperature