Pelagosite
Encyclopedia
Pelagosite is a variety of calcite
(Ca
C
O
3) whose type locality
is the Croatia
n island group of Palagruža
(Italian Pelagosa, whence the name) in the middle of the Adriatic. It was identified by R. Moser in Mineralogische und petrographische Mitteilungen, new series (Vienna) 1 (1878), 174. It has a higher content of magnesium carbonate
, strontium carbonate
, calcium sulfate
(gypsum
) and silicon dioxide
(silica) than is found in typical limy sediment
s elsewhere. It occurs as a superficial calcareous
crust no more than a few millimetres thick, which is generally white, grey, or brownish with a pearly lustre
. It was believed to be formed in the intertidal zone
by saltwater spray and evaporation
, but an algal contribution has recently been suggested (Montanari and others (2007)), following an overlooked earlier proposal by E. Onorato in 1926.
Calcite
Calcite is a carbonate mineral and the most stable polymorph of calcium carbonate . The other polymorphs are the minerals aragonite and vaterite. Aragonite will change to calcite at 380-470°C, and vaterite is even less stable.-Properties:...
(Ca
Calcium
Calcium is the chemical element with the symbol Ca and atomic number 20. It has an atomic mass of 40.078 amu. Calcium is a soft gray alkaline earth metal, and is the fifth-most-abundant element by mass in the Earth's crust...
C
Carbon
Carbon is the chemical element with symbol C and atomic number 6. As a member of group 14 on the periodic table, it is nonmetallic and tetravalent—making four electrons available to form covalent chemical bonds...
O
Oxygen
Oxygen is the element with atomic number 8 and represented by the symbol O. Its name derives from the Greek roots ὀξύς and -γενής , because at the time of naming, it was mistakenly thought that all acids required oxygen in their composition...
3) whose type locality
Type locality (geology)
Type locality , also called type area or type locale, is the where a particular rock type, stratigraphic unit, fossil or mineral species is first identified....
is the Croatia
Croatia
Croatia , officially the Republic of Croatia , is a unitary democratic parliamentary republic in Europe at the crossroads of the Mitteleuropa, the Balkans, and the Mediterranean. Its capital and largest city is Zagreb. The country is divided into 20 counties and the city of Zagreb. Croatia covers ...
n island group of Palagruža
Palagruža
Palagruža is a small, remote archipelago of dolomite in the middle of the Adriatic Sea in Croatia. It consists of one main island, called Vela or Velika Palagruža, and one smaller one, Mala Palagruža, and there are twenty or so other closely associated rocks or reefs...
(Italian Pelagosa, whence the name) in the middle of the Adriatic. It was identified by R. Moser in Mineralogische und petrographische Mitteilungen, new series (Vienna) 1 (1878), 174. It has a higher content of magnesium carbonate
Magnesium carbonate
Magnesium carbonate, MgCO3, is a white solid that occurs in nature as a mineral. Several hydrated and basic forms of magnesium carbonate also exist as minerals...
, strontium carbonate
Strontium carbonate
Strontium carbonate is the carbonate salt of strontium that has the appearance of a white or grey powder. It occurs in nature as the mineral strontianite.- Chemical properties :...
, calcium sulfate
Calcium sulfate
Calcium sulfate is a common laboratory and industrial chemical. In the form of γ-anhydrite , it is used as a desiccant. It is also used as a coagulant in products like tofu. In the natural state, unrefined calcium sulfate is a translucent, crystalline white rock...
(gypsum
Gypsum
Gypsum is a very soft sulfate mineral composed of calcium sulfate dihydrate, with the chemical formula CaSO4·2H2O. It is found in alabaster, a decorative stone used in Ancient Egypt. It is the second softest mineral on the Mohs Hardness Scale...
) and silicon dioxide
Silicon dioxide
The chemical compound silicon dioxide, also known as silica , is an oxide of silicon with the chemical formula '. It has been known for its hardness since antiquity...
(silica) than is found in typical limy sediment
Sediment
Sediment is naturally occurring material that is broken down by processes of weathering and erosion, and is subsequently transported by the action of fluids such as wind, water, or ice, and/or by the force of gravity acting on the particle itself....
s elsewhere. It occurs as a superficial calcareous
Calcareous
Calcareous is an adjective meaning mostly or partly composed of calcium carbonate, in other words, containing lime or being chalky. The term is used in a wide variety of scientific disciplines.-In zoology:...
crust no more than a few millimetres thick, which is generally white, grey, or brownish with a pearly lustre
Lustre (mineralogy)
Lustre is a description of the way light interacts with the surface of a crystal, rock, or mineral. The word lustre traces its origins back to the Latin word lux, meaning "light", and generally implies radiance, gloss, or brilliance....
. It was believed to be formed in the intertidal zone
Intertidal zone
The intertidal zone is the area that is above water at low tide and under water at high tide . This area can include many different types of habitats, with many types of animals like starfish, sea urchins, and some species of coral...
by saltwater spray and evaporation
Evaporation
Evaporation is a type of vaporization of a liquid that occurs only on the surface of a liquid. The other type of vaporization is boiling, which, instead, occurs on the entire mass of the liquid....
, but an algal contribution has recently been suggested (Montanari and others (2007)), following an overlooked earlier proposal by E. Onorato in 1926.