Malta is very well known for its Limestone which is a sedimentary rock. This rock is mainly composed of minerals such as, calcite and aragonite, which are practically different forms of calcium carbonate (CaCO3). In this case ARAGONITE is mainly a carbonate mineral, and is in fact an attractive mineral in its own right.
ARAGONITE is a ‘polymorph’ of calcite, which means that it has the same chemical qualities as calcite but is has a different structure, different symmetry and different crystal shape. Aragonite’s more compact structure is composed of triangular carbonate ion groups with a carbon at the centre of the triangle and the 3 oxygens at each corner. Unlike in calcite the carbonate ions do not lie in a single plane pointing in the same direction. Instead they lie in two planes that point in opposite directions; destroying the trigonal symmetry that is characteristic of calcite’s structure. Aragonite has an orthorhombic symmetry, whilst calcite forms in trigonal crystals. Thus in technical terms these two minerals (Aragonite & Calcite) differ only in their crystallisation.
This crystallization process is called ‘Paramorph’: Calcite paramorph after Aragonite. A pseudomorph involves two minerals with an identical composition but different crystal structures. The original mineral forms, but conditions then cause it to be unstable; so over geologic time, these two minerals transform into the other mineral with the same chemical structure while retaining the original crystal shape.
ARAGONITE is technically unstable at normal surface temperatures and pressures. It is stable at higher pressures, but not at higher temperatures such that in order to keep aragonite stable with increasing temperature, the pressure must also increase. If aragonite is heated to 400 digress C, it will spontaneously convert to calcite if the pressure is not also increased. Calcite is the more stable mineral, but under certain conditions of formation the crystallization process of calcite is somehow discouraged and aragonite will form instead. The magnesium and salt content of the crystallization fluid, the turbidity of the fluid and the time of crystallization are decidedly important factors amongst others.
Sedimentologists are very interested in aragonite and calcite stability fields because the conversion of aragonite to calcite after deposition has a distinct effect on the character of the sedimentary rocks. High pressure, low-temperature rocks of the blue schist metamorphic facies often contain veins of aragonite instead of calcite.
In Malta aragonite is mainly composed of calcium carbonate and is believed to be a constituent of many sea creatures’ shell structures in minute forms. Most bivalve animals and corals secrete Aragonite for their shells and pearls. Groundwater or seawater which would have found their way into a particular sediment (by tectonic movements or seepage over long periods of time) dissolves calcium carbonate. This environmental sensitive process depends on a delicate balance between temperature, water chemistry and carbon dioxide levels in the air.
As the mineral-saturated water (which we call ‘the soup’ as it contains nutritional wealth of natural minerals such as sodium, chloride, potassium, calcium, magnesium, copper, zinc amongst other beneficial trace elements) encounters surface conditions, this dissolved matter precipitates in layers of Aragonite ( or even Calcite). If heat and pressure persists over long periods of time Aragonite may even turn to travertine (many Maltese know this travertine as Gozo hard Stone- looking similar to the slabs covering the facade of the new parliament building in Valletta).
It might be interesting to note that the Maltese Islands are located on a broad platform extending from Northern Africa to Sicily, which divides the Mediterranean Sea into an eastern and western basin. The strata exposed on the islands range from Upper Oligocene to Upper Miocene in age and are predominantly carbonates with one pelagic shale unit. The mid-tertiary was a tectonically active time in the central Mediterranean. Malta’s location on a shallow, relatively stable platform in the center of a tectonically active Mediterranean, places it an interesting setting for diagenetic study.
Unlike recent carbonate sediments, the original mineralogic composition of the Lower coralline Limestone was dominated by high magnesian and low magnesian calcite with minor amounts of aragonite. This is the Polymorph process of both Aragonite and Calcite. Thus it can be easily said that Malta has always been a region of continued carbonate sedimentation for a considerable period prior to the Miocene.
The picture above is a sample of rough Aragonite rock (Amber colour brown with striations containing various sediments of minerals and sand) which has been extracted ( below 180 feet) from a closed down quarry in the South of the island.
On polishing this aragonite the stone turns into a myriad of fantastic pictures reflecting the Maltese Miocene Stratigraphy. Gemstones Malta Ltd has patiently turned these pieces into wonderful works of jewellery art.
METHAPHYSICAL Properties, Myths and Lores:
Astrological Sign: Capricorn, Cancer
Aragonite is a reliable earth-healer and is attuned to Gaia. This stone transforms geopathic stress and clears blockages even at a distance. It stabilizes the Sacral and Solar Plexus Chakras, deepening the connection between Earth and Self. It makes us more physical aware of our Higher Self, while at the same time helps us to stay in tune with the Earth Spirits so that we may better connect with the two.
Aragonite acts as a stabilizing stone and can be helpful for those who have focused solely on spiritual pursuits to the exclusion of other necessary tasks. It assists those who need to release issues from the past as well as attachments in the present.
This mineral is very helpful for students as it helps with concentration, especially those studying arts and sciences; aragonite can help to ground spiritual growth into the lower chakras, raising the overall vibration of the body thus can help to speed up the recovery from broken bones and nerve damage; sleeping with Aragonite under the pillow helps to relieve insomnia; if carried in jewellery form it helps grounding influence throughout the day.
Overall Aragonite is a world teacher for all humanity, facilitating macrocosmic awareness and appreciation of creative forces of nature.
Aragonite works well with Herderite, Natrolite, Phenacite and all forms of Azeztulites.
The above technical studies have been extracted from thesis and other studies compiled by renowned Maltese and foreign authors and geologists at the University of Malta.
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