Ice Ic
Ice Ic is a metastable
Metastability describes the extended duration of certain equilibria acquired by complex systems when leaving their most stable state after an external action....

Cubic crystal system
In crystallography, the cubic crystal system is a crystal system where the unit cell is in the shape of a cube. This is one of the most common and simplest shapes found in crystals and minerals....

 crystalline variant of ice
Ice is water frozen into the solid state. Usually ice is the phase known as ice Ih, which is the most abundant of the varying solid phases on the Earth's surface. It can appear transparent or opaque bluish-white color, depending on the presence of impurities or air inclusions...

. The 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...

 atoms are arranged in a diamond
In mineralogy, diamond is an allotrope of carbon, where the carbon atoms are arranged in a variation of the face-centered cubic crystal structure called a diamond lattice. Diamond is less stable than graphite, but the conversion rate from diamond to graphite is negligible at ambient conditions...

 structure. It is produced at temperatures between 130 and 220 K
The kelvin is a unit of measurement for temperature. It is one of the seven base units in the International System of Units and is assigned the unit symbol K. The Kelvin scale is an absolute, thermodynamic temperature scale using as its null point absolute zero, the temperature at which all...

 (−140 and −50 °C), and can exist up to 240 K, when it transforms into ice Ih. It may occasionally be present in the upper atmosphere.

Ordinary water ice is known as ice Ih, (in the Bridgman
Percy Williams Bridgman
Percy Williams Bridgman was an American physicist who won the 1946 Nobel Prize in Physics for his work on the physics of high pressures. He also wrote extensively on the scientific method and on other aspects of the philosophy of science.- Biography :Bridgman entered Harvard University in 1900,...

 nomenclature). Different types of ice, from ice II
Ice II
Ice II is a rhombohedral crystalline form of ice with highly ordered structure. It is formed from ice Ih by compressing it at temperature of 198 K at 300 MPa or by decompressing ice V. When heated it undergoes transformation to ice III....

 to ice XV
Ice XV
Ice XV is a crystalline form of ice, the proton-ordered form of ice VI. It is created by cooling water to around 130 K at 1 GPa .Ordinary water ice is known as ice Ih,...

, have been created in the laboratory at different temperatures and pressures.
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