  An independent analysis of Borexino single event energy spectrum of recoil
electrons and alphas was carried out. We compared two sets of single event
sources. The first set is similar to the one used in Borexino Collaboration
analysis. The second set additionally includes the scattering of
$^{40}$K-geo-($\bar{\nu} + \nu$) on scintillator electrons. We found two
equivalent minima for $\chi^2$ for second set. The one is for total counting
rates $R(^{40}$K-geo-$(\bar{\nu} + \nu)) = 0.0$ and $R(^{210}$Bi) = 10
cpd/100t. The other one is for $R(^{40}$K-geo-$(\bar{\nu} + \nu)) = 7.05$
cpd/100t and $R(^{210}$Bi$) = 6$ cpd/100t. We performed MC pseudo-experiments
and found that we do not have enough statistics and need to know the bismuth
concentration in the scintillator for definite measurement of potassium
abundance in the Earth. The possibility of building a next-generation detector
for looking for the $^{40}$K-geo-($\bar{\nu} + \nu$) flux is being considered.
