Georgia is rich in metalliferous and non-metalliferous deposits, mineral and fresh water
basins and ore manifestations; facing and industrial stones occupy special place among them.
Our country has great experience in mining and processing of them; this material has been
widely applied in both secular and religious buildings.
In 80-es of the last century there was mined 1.5mln.m3 facing stone: the Bolnisi tuff,
Marneuli basalt, Kursebi teschenite, Salieti marble, Eklari limestone etc.; they were applied
in producing blocks, plates, steps of stairs, decorative gravel etc. most of that was exported.
At present the mining and processing of facing stones (except of few cases) is
occasional. Only several producers manage to fulfill very few, generally local, orders. The
country looses significant contributions, local people are unemployed; there is practically no
mechanism for suggesting these material values to the market while the inner consumer
market is oversaturated with low quality and cheep (Chinese, Iranian, Greek) facing stones.
In Georgia there are known more than 360 deposits and ore manifestations and their total
value in the bowels of the earth reaches about 20 billion USD.
Georgian stone is distinguished for its ornamentality, low radial activity and good
physical-mechanical properties. It occurs in all the regions of Georgia and the significantly
increased demand makes firm ground for the development of small and medium business.
The Bolnisi tuff is noteworthy among the facing stones; it is characterized by variety of
kinds; the facing of the Bolnisi Sioni and Tsugrugasheni churches is the evidence of its usage
in the past.
The Farkhalo tuff deposit site is built by Upper-Cretaceous and quaternary sediments.
The Upper-Cretaceous is represented by Lower Turonian, Upper Turonian-Coniacian and
Lower Santonian.
The Farkhalo tuff mine, functioning since 1935, is in the Bolnisi ore-bearing field. It is
distinguished by variety of tuff considering its composition, grain kinds and color:
homogeneous, greenish tuff-breccia, decorative tuffs.
In the deposit there are spread tuffs and greenish tuff-breccias, decorative tuffs, tuffgritstones and thin liparite dikes; tuff-breccia and greenish tuff are developed in northern,
western and partly southern parts of the region.
From the decorative point of view noteworthy are the decorative, spotty, striped,
monotonous and wavy varieties.
Petrographically the decorative tuff represents altered liparitic tuff; there are observed
rock relicts of porphyritic structure. Porphyritic inclusions are represented by quartz and
plagioclases of albite-oligoclase series. Some phenocrysts of plagioclases are carbonized. The
basic mass is entirely kaolinized and cilicificated. Intensive pyritization is characteristic here;
finest pyrite grains are scattered throughout the basic mass; they are entirely limonitized.
In some thin sections there are observed fragments of volcanic glass or petrosilex. In
some of them there are scattered quartz and plagioclase thin grains throughout the basic
mass (generally volcanic glass); thus the rock was called - “welded tuff”.
In the deposit there are distinguished the following varieties of the facing stones:
1. Yellow banded ones
2. Yellow or sometimes gray ones with brown small or bigger spots
3. Graysh-yellow ones with small brown spots here and there
4. Green monotonous tuffs
At present the Farkhalo tuff is processed using modern technologies and factually there
is no waste.
Among the ten productive deposits of the chalcedony-agate group, known in Georgia,
the Akhaltsikhe deposits are especially significant.
The group of the Akhaltsikhe agate deposits consists of the two main independent
deposits – the Shurdo and Pamachi deposits- related to so called Akhalstikhe Depression. The
agate-bearing deposits are related to the Middle-Eocene igneous formations that are divided
into three series: colored tuffogene, tuff breccias and upper layered tuffogene. As for the
agate content, especially significant is the dark variety of the Middle-Eocene tuffs of andesite
composition. Agates are generally located in the andesite, tar-like black pitchstone
comprising zones and in broken zones.
The Shurdo agate deposite is located in the Akhaltsikhe region, in the Shurdo village in
10-15 km to the north-east from the Akhaltsikhe railway station at 820-1600m above sea
level; it represents the northern band of the Akhaltsikhe agate deposits.
The deposit consists of the Agara, Agarisghele, Mitsuri, Sakhlebi, Tsokhtevi, Sviri,
Gurkeli, Boga, Khamura regions. The northern agate-bearing band is 29 km long and 0.5km
in width. It consists of Middle and Late Eocene augite-plagioclase bearing andesites where
sporadically occur nested bodies. The nests are generally of two types: almond-shape and
nodulous; the almond-shape agate is of zonal-concentric structure and the nodulous one is
comparatively homogenous and mostly is used for technical purposes. Agate is of various
colors; there occur blue, bluish, red, brown and light grey varieties. The Shurdo agates are
characterized by good decorative features.
Especially noteworthy are the Goderdzi perified trees with their unique museum pieces
and chalcedonized and opalized varieties. To the south of the Meskhety Range, on the
Goderdzi Pass adjoining territory, at the waterfalls of the Dzindze (Dzindzisu) and Achara
Water rivers, in the Neocene igneous (pyroclastic) rocks there is a petrified forest where
there can be found unique pieces of fossilized plants and petrified trees. The Goderdzi
Perified Forest is one of the most uncommon and most important natural monuments notable
for its locality, fossilized flora and petrified trees representing unique museum pieces.
The Goderdzi Perified Forest is spread from the Adigeni region, the Utkino village part
(at 1450m above sea-level) to the Upper Achara, the Riketi village (at 1100m above sealevel). It occupies about 70-80 km2. In the central part of the Petrified Forest there is the
Goderdzi Pass where there goes the Akhalkalaqi-Batumi motorway.
The relief of the Goderdzi suite territory (natural monument) complex enough –
mountainous and of severe topography; it consists of the Upper Miocene – Lower Pliocene
deposits represented by igneous rocks – volcanic breccias, lava sheets and conglomerates.
Maximal thickness reaches 250m. Just along the road there crop out the main igneous rocks
representing best visual points from the geological point of view. On the rocks along the
road, in the volcanic breccias there are distinctly observed natural outcrops of fossilized flora
and petrified trees that are of various sizes, form and orientation.
Almost on all over the thickness of the Goderdzi volcanogenic-sedimentary suite there
are fallen petrified trees that are irregularly distributed throughout the rocks. They occur in
all the kinds of rocks representing the Goderdzi suite indicating that the formation of the
petrified trees and the suite constituting rocks was simultaneous. After the volcano eruption
the forest was covered by volcanic ash that caused the felling of trees, braking of boughs and
branches and their petrification. In the rocks the inclusions of petrified trees are disposed
horizontally, vertically or at various angles. The inclusions are represented by certain logs of
3m long and by fragments of various forms and sizes; their diameter varies within 5-70 cm.
Sometimes there occur inclusions up to 1m in diameter. The thin sections made of the
petrified tree sample show that the structure of the tree is linear-cellular and almost the
whole initial mass is replaced by opal and chalcedony and the fissures and voids are filled up
by chalcedony and quartz; in some samples of petrified tree together with opal and
chalcedony, along the stripes there can be observed segregations of fine-grained pyrite.
Generally the processes of petrification of trees and silicification took place simultaneously;
its organic material was almost entirely replaced though its initial structure remained
uninjured.
Noteworthy is that in chacedonized trees the initial structure of the tree is better
preserved than in opalized ones; the chacedonized trees are denser and better stand
processing while making articles of them but opalized trees are comparatively fragile; the
strength of both kind, according to Mohs scale varies within 4 – 6.5. The petrified trees are
brown, yellow, white, red and black. Often these colors are characteristic of one and the
same sample and sometimes they alternate making the sample more decorative.