3:30 PM - 5:00 PM
[O08-P44] Toward "Solid State Chromatography" 3rd Report
-Separation and identification of fossils from sedimentary rocks-
Keywords:microgravity, magnetic separation, diamagnetic material, microfossil, solid state chromatography
Our group of the Science clubs in the evening course of high schools has so far proposed the principle of separating and recovering mixtures of diamagnetic solid particles according to the type of material. We have also manufactured and experimented with the apparatus. Last year, a magnetic circuit with permanent magnets was improved. The maximum magnetic field between the poles of the magnetic circuit exceeded 1 T. This allowed for increased separation accuracy. The resolution of magnetic separation is 0.4×10-7 emu/g.
In the present study, fossils from a Quaternary mudstone (Ujiyamada, Kyoto) containing fossil shells (CaCO3) were separated using this apparatus. The rock samples were broken down into their constituent particles using the freeze-thaw method. The solid sample was sieved. Subsequently, the fine particles adhering to the surface of the solid sample were washed with alcohol. Magnetic separation of rock constituent particles was carried out using an instrument with increased resolution. Mineral constituent particles, paramagnetic and ferromagnetic particles, were attracted in the direction of the magnetic field centre and did not exit the magnetic field. The diamagnetic particles were in translational motion out of the magnetic field. Shell fossils are composed of CaCO3 and are diamagnetic. The extracted diamagnetic particles could be assumed to be CaCO3 from the calibration curves. The composition of these particles was analysed using SEM-EDS. As expected, its composition was dominated by Ca, C and O. The diamagnetic solid particles were therefore identified as CaCO3. The extracted fossils are considered to be fragments of shell fossils based on their shape.
It is now possible to separate fossils from rock constituent particles using magnetic susceptibility. Since the targeted particles could be extracted from the mixture of particles, this apparatus can be utilised as a 'solid state version of chromatography'. In the future, we would like to aim at extracting foraminifera (CaCO3) , radiolarian (SiO2) and siliceous algae (SiO2). The apparatus for efficient separation of large quantities of mixed material samples, including fossils, will be developed.
In the present study, fossils from a Quaternary mudstone (Ujiyamada, Kyoto) containing fossil shells (CaCO3) were separated using this apparatus. The rock samples were broken down into their constituent particles using the freeze-thaw method. The solid sample was sieved. Subsequently, the fine particles adhering to the surface of the solid sample were washed with alcohol. Magnetic separation of rock constituent particles was carried out using an instrument with increased resolution. Mineral constituent particles, paramagnetic and ferromagnetic particles, were attracted in the direction of the magnetic field centre and did not exit the magnetic field. The diamagnetic particles were in translational motion out of the magnetic field. Shell fossils are composed of CaCO3 and are diamagnetic. The extracted diamagnetic particles could be assumed to be CaCO3 from the calibration curves. The composition of these particles was analysed using SEM-EDS. As expected, its composition was dominated by Ca, C and O. The diamagnetic solid particles were therefore identified as CaCO3. The extracted fossils are considered to be fragments of shell fossils based on their shape.
It is now possible to separate fossils from rock constituent particles using magnetic susceptibility. Since the targeted particles could be extracted from the mixture of particles, this apparatus can be utilised as a 'solid state version of chromatography'. In the future, we would like to aim at extracting foraminifera (CaCO3) , radiolarian (SiO2) and siliceous algae (SiO2). The apparatus for efficient separation of large quantities of mixed material samples, including fossils, will be developed.