Pizolits or " cave pearls ", the best of which look exactly the natural pearls, occupy the special place among the chemical formations of caves due to their nature and specific features of development [17],[19]. In Armenia cave pearls have been discovered by the author in August of 1983. First they were found in the tunnel - bridge called "Devil’s bridge" (Satani Kamourdg), which is located in Goris region, Zangezour (Figure 11).

Figure 11. Devil`s bridge plan and the profile.

The bridge is one of the most notable natural monuments in Armenia [20]. The Vorotan river flows through the cave. Due to the destructive influence waterflow, the entrance of the cave is three times larger than its exit. The ceiling of the cave is completely covered by gigantic shield stones. The ceiling has been destroyed in two places and the sun light penetrates the cave. The waterlike edgeline of the cave shows that during floods, the river flows from one wall to another in the cave, it is drawn on the figure 11. When the flow of the river is weak, a lake is formed in the cave.

20 meters up from the bridge, the canyon is very narrow and the river flows from wall to wall, so the walls of the canyon look like those of the cave. Previously, the bridge was two times bigger, but later on the upper half of it was destroyed. Presently, only four meters wide arch and the unusual form continuation of the edge line of the river ( see Figure 11, plan ). Four springs of mineral water are located above the cave. The fifth spring is 200 meters below the latters, on the bank of the river, below the Devil’s bridge. The springs have different temperatures and strengths of flow, the values for which are shown below [21]:

Table 8. Values of spring flows and temperatures of waters

Near the first spring, the remains of the ancient bath can be found.

The waters of the first and second springs penetrate into the tunnel - cave. The consistency of their waters is the following [21]:

Table 9. The chemical consistency of Tatev - 1 and Tatev - 2:

The floor of the cave is almost entirely covered by a lake. The area of the pearls development is A - part of the cave, which is 1 - 2 meters above the water level and has the surface of approximately 30 m². A natural laboratory for the development of pearls is located at this place, where it is possible to investigate the mechanism of pizolit formation. The pizolits are located in waterholes, so called " nests ". The diameter of the area where a water drops dripping from the ceiling. The edges of the nests correspond to this diameter and that is the place, where the pizolits are formed around various crystallization centers. The sizes of waterholes, which get water only from one point of the ceiling, are approximately the same.

S = 6 X 3 » 20 cm²

V = 20 x 3 = 60 cm²

These are so called " unit waterholes " ( Figure 12 ).

Figure 12. The waterhole with one feeding point.

There are bigger waterholes with the surface 20 x 20 cm², but despite of the waterholes, the crystallization centers of large size are formed only in those areas, where the waterdrops fall from the ceiling ( Figure 13 ).

Figure 13. The plan and the profile of the waterholes with two feeding points.

Pizolits vary considerably ( from d = 1 - 2 mm to d = 15 - 20 mm ) in their sizes. The biggest pizolit is shown on the Figure 14 ( a - the view from above, b - the view from aside ).

Figure 14. The Devil`s bridge the biggest pizolit. a - the view from the upper side, b - the view from aside.

It was definitely formed by the combination steadily enlarging pizolits in the waterhole shown in the Figure 12. Probably, the deviation from the round shape, which is inherent to pizolits, takes place when the free rotation of the pizolit to all directions is Iimited. It is possible to track a particular order in the way the pizolits are arranged in the waterholes, where the pizolits of different sizes as a rule may be contained. The pizolits of the smallest sizes are located at the bottom of waterholes and the sizes of pizolits grow towards the surface of the waterhole (Figure 15).

Figure 15. The pizolits lay - out in the waterhole due to their sizes ( the view from aside ).

In a number of unit waterholes, which have the surface of approximately S= 10 x 15 = 150 cm² more than a hundred of small and middle-sized pizolits can be found. Big pizolits diameters are 1 cm and larger can be found only on outer surface and are limited in number by the surface area.

Let’s use S as the surface area of the waterhole. In that case the surface of a section passing the pizolit centre will be:

s = p r² = p d² / 4

The number of pizolits, having 1 cm diameter will be: n₁ = 4S /p d² = 4S / 3 » 1,3S

The number of pizolits, having 0,5 cm diameter will be: n_0,5 = 4S / 3x0,25 » 5,3S

The number of pizolits having 0,3 cm diameter will be: n_0,3 = 4S / 3x0,09 » 14S

The number of pizolits, having 0,2 cm diameter will be n_0,2 = 4S / 3x0,04 » 33S

This values are in correlation with a crystallization speed.

The centres of crystallization for pizolits are stalactites splinters and other crystal matters, which diameter does not exceed 1-2 millimeters. This is the most common size and the crystallization centres with bigger diameters can be met not often. Sometimes it is possible to see thin stalactites broken way from the ceiling as well as grass stalk. The latters serve as crystallization centres for long pizolits.

In the beginning, the embryos are shapeless, but as they grow larger, they start to bother each other’s growth and revolving like in a mincing - machine, thereby getting a round shape (Figure 16 b, c, d ).

Figure 16. The pizolits formation ( the view from aside ) a - embryos, b, c, d - forming pizolits.

When pizolits grow too large, those of the upper layer come out of water. If there is a drop of water on or around the pizolits, then it can move pizolits with diameter up to 2 cm, which makes the stones to grow further (Figure 17a, 17a` ).

Figure 17. The forming pizolit fiture alteration ( the view from aside ) a, a` - growing pizolit; b, c, d - the fossil stages of the pizolit.

If the waterdripping stops, the crystals start to develop in the part of a pizolit covered by water and the pizolit look like a thorny hedgehog subsequently (see the Figure 17b ). Eventually it loses its initial round shape smoothness and becomes petrified (Figure 17c, 17d ). In general, as long as water drips on the surface of the waterholes, the pizolits have better exterior outlook and they are smooth. In the waterholes with no supply of fresh water the petrifaction process begins, as a result of which a bottom, walls and pizolits in the waterholes are surrounded with thornlike crystals. Due to it, the pzolits stick to each other and to a bottom of the waterholes (see Figure 18).

Figure 18. The pizolits gradual fossel ( the view from aside ).

Such petrified waterholes get fresh water from other waterholes. This fact suggests that petrifying pizolits must be located at lower part of a scorching slope. And this is exactly what happens in reality ( Figure 19 ).

Figure 19. The division of petrifying pizolits on the lower parts of the slope ( the view from aside)

In the places, where the waterholes are very shallow, an alga starts to grow. Afterwards, the alga decomposes, obtaining dirty green colour. These results in a specific colouring of the surface growing pizolits and the pizolits, which partially stand out of water.

The ability of waterdrops to form pizolits largely depends on their falling speed or, correspondingly, on the height of the ceiling. The waterdrops fall from 2.5 meters height under the Devil’s bridge. At another place this height equals to 1.5 meters. In places, where the height of ceiling is less than 1.5 meters, pizolits are not being formed. Probably, the kinetic energy of the falling drops is not sufficient for revolving crystallization centres and, consequently, forming pizolits. There is a particular correlation between the depth of the waterholes and the falling height of pizolits. After using our data and the data from [17], the following graph can be attained (see the Figure 20). Here x axis (H) represents the height of ceiling in meters and y axis (h) represents the depth of the corresponding waterholes. As it can be concluded from the graph, after a definite height of the ceiling ( » 25m ), the waterholes do not get any deeper as the energy of a drop is not sufficient for reaching the bottom of the waterhole.

Figure 20. The connection between the fall height of water drops and the diameter of forming pizolits.

The energy of a falling drop diminishes also with deepening of the waterhole. That is why, there are no pizolits in the waterhole deeper than 5 cm under the Devil’s bridge, although there are waterdrops with different levels of energy. That reason is in the basis of the following phenomenon, though there are drippings in some places but, as soon as, the banks of the waterholes have lifted and they have become approximately 1 cm deeper, so the pizolits begin to crystallize again in such waterholes. The strength of a drop impact doesn’t reach them and the lumps stay motionless on the floor ( Figure 21 ).

Figure 21. The phenomenon of pizolits crystalization, which depends on the waterhole becoming deeper ( the view from aside ).

In the tunnel-cave, there is a big lake with the width 40 cm and the length 100cm. The pizolits are growing, smooth and shining in its upper part, where the water depth lifts for 1,5 cm on the pizolits and at the foot of it, where water becomes deeper for 1-3 cm, the pizolits are "dying" (Figure 22).

Figure 22. " Living " pizolits and " dying " pizolits in one of the big waterhole under the Devil`s bridge ( the view from aside ).

The reason is the same, the energy weakening of the drops, which hit water because of the waterhole becoming deeper. Time of the fall of the drop, falling from the ceiling is defined by the formula of the way, which a dripping body passes in its free fall. S=gt²/2, where g is the stability of a free fall (9,8m /sec² ), t is the time of the fall, S is the height of the ceiling in this case t= 2S/g.

In the case of 5 meters height, the time of a drop fall is:

t = ( 2 x 2,5/9,8 )^0,5 » 0,1 seconds.

The time of one drop fall from the ceiling is (» 0,1 seconds), so there must not be a constant sheild for a pizolit formation and it means that the minimum interval of drops must be 0,1 seconds. It is that way round in reality. It is 5-10 seconds on an average, there are also up to 60 seconds.

If the dripping is quick, shield like nearly all the time, there are neither normally formed waterholes, nor pizolits. A strong shield chuck everything out. The volume of a drop on a average is 0,03 milliliter, so the feeding regime of a waterfall, which feeds from one feeding point of the ceiling, will have the following values, which depends on the frequency of drops ( Table 10 ).

Table 10. The feeding regime of waterholes depending on the drops frequency.

The pizolits of the Devil’s bridge are the kind of those unique formations, which age is known precisely. So in 1970, the considerable part of the Vorotan river waters was transferred to the other channel with the goal to make the Tatev HPP to work and the floor of the cave under the Devil’s bridge has been open in some place. The pizolits with the diameter up to 5 mm. are there in that part, the age of which exceeds 13 years (the investigation were done in 1983). We don’t know when their formation began after 1970 but one thing is precise. It is that the age of those pizolits doesn’t exceed 13 years.

We estimated the age of the Devil’s bridge on the basis of the kinetic dimensions. The dimensions, in the basis of which there are the experimental results, gave the following volume: The volume of the bridge is approximately 20x20x40=16000m³.

A salt layer with approximately 1cm² surface and 0,1 cm thickness appears during three months on the branch of a tree, which is put under the shield, which has the flow of 5 drops in a minute. It makes 10 x 0,1 x 4 = 4 cm³ sediment every year. In the same period of time the quantity of running water will make:

0,2( ml/min ) x 60 x 24 x 365 = 105120 ml/year » 100 litters/year.

The sediment, separated from 1 litter of water in one year, makes:

4 / 100 = 4 x 10^-2 cm³

The total discharge of mineral springs waters (see the Table 8).

4,8 + 4,1 + 1,4 + 1,1 + 0,1 = 11,5 lit /sec.

The yearly total expenditure of waters:

11,5 x 60 x 24 x 365 » 6 x 10⁶ litter/ year.

The total quantity of the sediments appeared in 1 year:

4 x 10^-2 x 6 x 10⁶ = 24 x 10⁴ cm³ = 24 x 10^-2m³

The age of the bridge is;

16000 m³ /24 x 10^-2 m³ = 0,7 x 10⁵ = 7000 years

The second place of pizolits is the Arpa river valley, it is at a distance of 1 km from the Arpy village. The locality is called Dgrovank (the Monastery of Water). The Monastery of Water is a kind of a horseshoe like rock (Figure 23).

Figure 23. Dgrovank plan and the microscopic section ( AA₁ and BB₁ ).

Four vigorous springs come down the rock ( 1, 2, 3, 4 ). The second and the third springs come down the same level. They flow along the inclined slope and the first and the fourth springs come down several meters lower and form ravines ( see Profile AA₁ ) A piece of the part 3-4 are black sediments with the width 5m and 1,5-3 meter height, which are surprisingly like man’s sex organs (with sizes 0,4-0,7m), water is dripping under them. It is an ancient sacred place and the imprints of that sacred place are preserved. (Figure 24).

Figure 24. The view from aside of Dgrovank pagan sacred place ( 1 -3 thousand years before Christ ).

The pizolits, which are in the part of the third spring with the width 20m and 40m length (up to ravines connection place) (Figure 23, the shaded triangle), they are devided cone like, which peak is the spring and the spread part is that fragment, where the pizolits are rolling and accumulating. The slope bent is 10-15^O here. The slope is naked in this part because the pizolits come down all the time.

Two holes with 30 and 50 cm depth were digged for the pizolits volume estimation. Seven layers were discovered in 30 cm hole (Figure 25a).

Figure 25. The microscopic section from aside of pizolits accumulation place.

The layers of pizolits and peels were following each other under the upper petrified peel. All the pizolits are of the same size d=4-6 mm. There are several cm³ volume blocks of stones below, they are cemented on the surface. The shoolf, which has 50 cm depth, also has a layer structure ( Figure 25b ). Its lower layer is the preserved part of a moss structure, which didn’t get the structural unity. The peels of the surface are also cemented. It can be connected with the sharp alteration of water flow in that certain part. It repeated several times. Probably, it is the result of icing.

Dgrovank is in the direction of Mozrov aragonite cave [20]. The Mozrov aragonite arising thermal maters arose also Dgrovank pearls and then they passed to more lower horizon. The present Dgrovank springs places met a watertight layer (for example clay) and they were drained. The holes of old waters of 1,5-2,5m springs are lower than the level of the present ones. If Mozrov cave water formed pizolits, then pizolits must be aragonite. Aragonite was not discovered in the holes but there is an aragonite in the cave located at the bottom of the second spring. Pizolits lost their aragonite structure being small. At present, there is no pizolit formation in Dgrovank part. Pizolits appeared in the cave and then they were chucked out periodically during floods, accumulating near the exit of the second spring. The pizolits volume gives the opportunity to estimate the sizes of that cave, where they were formed. The total volume of pizolits makes approximately:

0,4x20x40/2=160m³.

The number of pizolit layer located on each other is:

n=40/0,4=100.

The volume of pizolits one layer is:

V=160/100=1,6m³.

According to the investigations done under the Devil’s bridge, 1² meter of a cave can give maximum 1 x 0,03 = 3 x 10^-3 m³ pizolits. Let’s thing, that the formation of each pizolit layer happens at the same time then they are chucked out by a flood from the cave, hew pizolits begin to form.

In that case, the surface S = 1,6 / 3 x 10^-3 = 0,53 x 10³ m² is necessary for the formation of 1,6m³ pizolits. It equals the cave, which has 5000m length and 10m width, the height of the ceiling of which must not be lower than 2 meters.

In reality, the waterholes, which form pizolits occupy the insignificant art of the cave floor. Consequently, the sizes of the unknown cave is incomparably big. So a great unknown cave with the length, reaching probably ten kilometers is located not far from the well-known Bears cave[20], between the Mozrov aragonite cave Dgrovank.