We present an analysis of the solar corona visual spectrum, captured during the total solar eclipse of 21 August 2017, in Salem, Oregon USA. The eclipse took place about 2 years before the solar minimum of the 25th solar cycle, that occurred on 2019/2020. The spectra were captured by two slitless spectrographs with different dispersions and include the two principal coronal emission lines Fe XIV and Fe X. Following the continuum subtraction of the K-corona, the very faint coronal emission line of Ar X 5533 A was detected. The slitless spectrograph also recorded the distribution of Ar X around the solar limb, which was compared to the distribution of the two principal ionized iron lines. A correlation between the distributions of Ar X and Fe XIV has been identified and an explanation is provided for the Ar X presence in the solar corona around the solar minimum periods. Simultaneous observations with the two-channel Lyot filter, tuned at the green and red coronal lines of iron, revealed different formations and structures that exist at the eastern solar limb, high in the corona and appearing at extended solar latitudes. Due to the moisture presence in the Earth's atmosphere, all obtained spectra during the solar eclipse contain also strong absorption lines of water vapor.