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Voropaev, et al.

minerals. Apparently, their extraction is associated with chemical composition of fresh scoria and lava samples
the dissolution of the rock. Furthermore, elements with collected by our team on Tolbachik lava field (TFE
variable valence such as Co, Fe, Mn, and Ni could be 2012 – 2013) is presented in Table 1. Similar analytical
reduced in the presence of oxalic acid to highly soluble results were reported in the form of BSE images and
compounds. Elements such as Al, Cu, Mn, Pb, Sr, and tables with the energy dispersive spectroscopy point
Zn were extracted by acetic acid much better than by analysis in a published paper. 18
pure water, that is, LC (ac) >10. Compared to lava, scoria is enriched with refractory
metals (such as Ca and Mg), but it is depleted with
5. Results and discussion volatile elements (such as Na and K). Our team analyzed
trace metals abundance of the above samples using AES
Liquid differentiation occurs in basaltic melts due with ICP-AES method in GEOKHI RAS on iCAP6500
to the contrasting roles of two types of structural (Thermo Scientific) and the results are presented in
components – first, network-formers; second, network Table 2. The procedure for preparing samples was
modifiers. According to the modern state of science, described in detail in a TFE study. 19
the basic structural unit – SiO tetrahedron – can In natural environment, many weeds (such as nettles)
4
form one-, two-, or three-dimensional networks and secrete acetic acid, whereas lichens secrete oxalic acid,
clusters. If the network is completely polymerized, mainly. Meanwhile, lichens are the most primitive
then each Si–O–Si bridging oxygen is shared by two species and are the first to populate fresh lava fields.
SiO tetrahedra. Usually, network-forming cations Having compared the values of the LC(ox)/LC(ac) in
4
(in silicate melts primarily Si , including Al , Fe , Table 3, we inferred that oxalic acid efficiently extracts
3+
3+
4+
and Ti ) are surrounded by oxygen ions in bridging some elements much better than acetic acid. Hence,
4+
position (Si–O–Si). However, network-modifying the appearance of lichens significantly accelerates
cations are surrounded by oxygen ions in non-bridging the process of biochemical weathering of magmatic
positions (Si–O–M), where M denotes the six-fold eruption products. We grouped the elements according
coordinated by oxygen network-modifying cations to the power of extraction by different organic acids, as
(as a rule, Mg, Fe[II], Ni, etc.). During melt separation, shown in Table 4.
the chemical elements are distributed among the two The mechanism of chemical weathering mainly
conjugates according to melt structure, which depends concentrates elements of the first group. For alkaline
on composition, the number of volatiles, pressure, and elements, nickel, chromium, and other metals that are
temperature. Finally, the solubility of an igneous rock part of the silicate matrix of the rock, mobilization is
will be determined by the stability of its constituent associated with its destruction. It is known that water is
minerals. an excellent solvent for rocks and minerals. The main
According to energy-dispersive X-ray analysis, main chemical reaction of water with minerals of igneous
rock-forming minerals of Tolbachik volcanic rock are rocks (hydrolysis) leads to the replacement of alkaline
Ca-rich plagioclase, Ca-Mg-rich pyroxene (diopside), elements’ cations of crystal lattice with hydrogen ions
Mg-rich olivine, and K-feldspar. Amount of minerals of dissociated water molecules, like
varies from sample to sample. Secondary minerals are
Mg-rich mica phlogopite (KMg (AlSi O )(OH)) and KAlSi O + H O → HAlSi O + KOH (III)
3
8
2
8
3
10
3
3
alunite (KAl (SO ) (OH) ). Moreover, a number of Cu, The resulting bases (NaOH, KOH, and others)
3
6
4 2
Zn, and Pb fumarolic minerals were found: tenorite compose an alkaline medium of the solution, in which
(CuO), chalcanthite (Cu(SO )·5H O), atacamite further destruction of the plagioclase crystal lattice
4
2
(Cu Cl(OH) ), pyromorphite (Pb (PO ) Cl), linarite occurs also, the interaction of water with rock minerals
4 3
5
2
3
(CuPb(SO )(OH) ), anglesite (Pb(SO ), and diopside leads to hydration, that is, the attachment of water
4
2
4
with Cu, Zn-impurities (CaMgSi O ). 13 particles to mineral particles, like
2
6
In general, basaltic lavas are prone to rapid
crystallization in an open system due to degassing 2Fe O + 3H O → 2Fe O ·3H O (IV)
2
3
2
3
2
2
and cooling. For example, a general sequence of the The second group, including vanadium, manganese,
17
Tolbachik fissure zone comprises the two extreme iron, cobalt, and titanium, is characterized by an
types of basalts, which differ primarily in the content order of magnitude higher extraction values in oxalic
of Mg and Al: Middle-K, high-Mg (Mg/Al: 2.1) basalts, acid solution compared with solutions of other acid.
and high-K, high-Al (Mg/Al: 0.45) basalts. Typical Taking into account the reducing properties of oxalic
12
Volume 22 Issue 1 (2025) 38 doi: 10.36922/ajwep.8113