Single-phase liquid inclusions

Single-phase liquid inclusions are not very common. Although many minerals are crystallized from homogeneous aqueous fluids, the temperature during their formation is much higher than the temperature on the Earth’s surface. Thus, primary homogeneous fluid usually separates in at least two phases – liquid and gaseous, forming water filling with a gas bubble. Totally liquid inclusions can be observed in crystals formed at low temperature and pressure, in low depth deposits.

Interference films in aquamarine. Very thin cavities with single phase liquid filling, forming interference films in aquamarine from Brazil. The interference colors are only observed under a very specific orientation of the sample; they are caused by so called thin-film interference, same phenomenon that causes colors of a drop of gasoline on water surface. Field of view 3.5 mm.


Also, sometimes they can be formed as a result of the separation of larger inclusions in several parts due to recrystallization of the cavities’ interior surface, phenomenon known as “necking down”. As a result, the gas bubble can be located in only one of the resulting separated cavities, while others will contain liquid phase only. In fluid inclusions studies, inclusions that suffered necking down process are not suitable for microthermometric analysis because their thermodynamic characteristics don’t correspond anymore to the primary entrapped fluid.

Several single phase liquid inclusions can be seen in this tourmaline. They are formed as a result of necking down process, responsible of the formation of “trichite” inclusions, typical for this gemstone. The central part of the large fluid inclusion and some others contain vapor bubbles, but some completely separated parts of the same originally united cavity are filled solely by liquid. Field of view 3 mm.