LoveStones

The rocks that make up my collection are mainly Peridotites, Peridotites with different degrees of serpentinization, Serpentinites and some Magnetites that over the years I have been collecting on my walks along the beaches and in the vicinity of the Rio Real riverbed in Marbella.

Peridotites are high-density, coarse-grained igneous rocks, formed mainly by the minerals Olivine and Pyroxene.

The name Peridotite comes from the gem Peridot, which is composed of light green Olivine.

Although they are mostly dark green rocks, peridotites can appear in different shades of yellow, brown, red and even blue, depending on the proportions of the minerals that compose them.

This is an ultramafic group of rocks, since they contain less than 45% of Silica (silicon oxide), being composed mainly of Magnesium (Mg) and iron oxides and characterized by their different proportions of Pyroxenes, Chromite, Plagioclase and Amphibolite.

Peridotites are the dominant rocks in the upper mantle of the earth, normally located at depths exceeding 200 kilometers and being difficult to find on the surface, as their main compounds degrade relatively easily in contact with air and water.

Peridotite outcrops in the earth's crust occur mainly in areas of continental subduction, where the collision of a tectonic plate against another has made them rise until they are exposed. They are of great scientific interest, since they provide data on the processes that occurred in the formation phase of our planet.

With a surface area of approximately 450 square kilometres, the Peridotite outcrop in the province of Malaga (Spain) is probably the largest on our planet and also the one with the greatest mineralogical diversity.

It emerged as a consequence of the collision of the Eurasian and African continental plates, which during the Oligocene period (between 34 and 23 million years ago) gave rise to the peridotite massifs of Ronda (called Sierra Bermeja) Ojén (Sierra de la Alpujata) Carratraca (Sierra de Aguas) and Casarabonela (Sierra de la Robla).

Serpentinization is a metamorphic process by which rocks low in silica, mainly peridotites, are transformed by oxidation into serpentinites.

Among other minor causes, serpentinization occurs when masses of ferromagnetic rock subjected to high pressures from the depths of the Earth's mantle begin to ascend towards the crust by the impulse of tectonic phenomena and collide with masses of water that infiltrate them (as a result of the reduction in density derived from the change in pressure), giving rise to a very significant increase in volume (between 30 and 40 %) and to processes of hydrolysis in which the original structure of the rock changes.

The process generates large amounts of hydrogen (H2) and is highly exothermic, causing temperature increases that can exceed 250º C.

The large amount of Hydrogen that is produced in the serpentine process has led to it being studied as a highly effective form of energy generation that is compatible with the conservation of the environment, since not only does it not cause carbon emissions, but it also leads to the reduction of the surrounding carbonates and sulphates, consuming CO2, which is why it is also being used to get rid of the main producer of the greenhouse effect, by storing it in the depths of the earth.

The energy generated in the process of serpentining one cubic meter of rock reaches approximately 660,000,000 Joules, enough to keep a 100-watt domestic light bulb on for about 80 days.

On the other hand, the production of hydrogen in the absence of atmospheric air (anaerobic conditions) generates Methane (CH4) and Sulphuric Acid (H2S) which in turn give rise to the formation of hydrothermal sources in which chemical organisms develop, so the most modern theories of evolution associate this process with the emergence of life on earth.

The name Serpentinization comes from the type of textures that the peridotites acquire after suffering this type of process, since originally having a uniform aspect, they go on to be crossed by veins of very different textures and colors that are due to the occupation and transformation of different compounds in the interior of the conduits through which the water infiltrated, acquiring an aspect that sometimes resembles that of the skin of a snake.

The name Serpentinite comes from the Latin word "Serpentinus", which means snake, and is due to the characteristic green color of the rock and the scale-like patterns it sometimes has, which make it look like the skin of a snake.

In some parts of the world the serpentinite is also called "infinite stone", because its veined and almost fractal structures, allow to lose the sight in them and fall into hypnotic landscapes.

The attractive designs and colors presented by the Serpentine have enamored artists since ancient times, having been used to create decorative and ornamental elements, as well as for the construction of buildings (College Hall of the University of Pennsylvania), coatings and furniture, as it is a rock almost as hard as marble, but unlike this, allows to obtain very bright finishes and highlight their natural enamel, through a slight and simple polishing.

The ancient Greeks believed that this wonderful stone could give clairvoyance and harmony to its bearers. And several African civilizations, among them the Egyptians and the Assyrians used it as a representative stone of fertility and abundance.

Today the "New Age" culture has once again drawn attention to these amazing stones, because in addition to other beneficial effects, it is claimed that they help to connect with the universal energy that resides in nature and to activate the Kundalini.

With an area of approximately one hundred square kilometres and situated between the municipalities of Marbella, Ojén and Mijas, the peridotite massif of the Sierra de la Alpujata is the second largest ultramafic outcrop in the province of Málaga.

It is mainly composed of peridotites from the upper mantle that ascended to the earth's crust as a result of the lithospheric shearing of the alpine folding that occurred during the Oligocene period (approximately 23 million years ago), undergoing metamorphic processes by which they became Magnetites and Serpentinites, mainly in their variety of Iherzolites.

The deposits of the Sierra de la Alpujata have been exploited throughout history for the great variety of minerals they contain. There are mines such as La Gallega, La Concepción or Peñoncillo or Los Linarejos, all of which have been abandoned to this day, where iron, talc, nickel, chrome, lead, cobalt and many other species have been extracted.

Singularly important was the Concepción iron mine, which began to be exploited in 1826 by "La Concepción Iron Mining & Steel Corporation", a company created by a famous businessman from Malaga named Manuel Agustín Heredia, who installed a foundry in which practically 75% of the iron extracted in Spain in the 19th century was produced and gave an important boost to the economic life of the area. The mine later passed into the hands of the English company "The Marbella Iron Ore Company Ltd", which kept it active until the last quarter of the 20th century, even installing a funicular railway by which they transported the iron to the sea, to be shipped to the United Kingdom.