Single-phase solid inclusions

This inclusions type is a very common one in nature. We observe such inclusions looking at rutile or tourmaline needles in quartz, pyrite or calcite crystals in emerald, zircon or apatite in sapphire, olivine or garnet in diamond, etc. They are just crystals of other minerals entrapped inside the host crystal. They can be formed before, together or after the crystallization of the host mineral (see “Classification by time of entrapment”).

Sometimes such inclusions are perfectly formed and represent a valuable object for collectors. They can be common or rare, and they can provide color or special optical phenomena to the gems. Many examples of single phase solid inclusions can be found in this website’s galleries.

Hollandite star in quartz from Madagascar. Field of view 6 mm.


Not all solid inclusions are minerals. Glass inclusions also can be found in minerals formed in magmatic deposits, but also in flux-grown synthetic crystals and heat-treated natural gems. In many cases the glass will also contain a gaseous bubble, so these inclusions are considered more in detail in the section of two-phase solid-gaseous inclusions..


Solid inclusions in synthetic Russian flux-grown emerald, corresponding to solidified amorphous molybdenum and vanadium oxide flux used as a grown medium for synthesis. Field of view 1.5 mm.



Vitreous inclusions in heat-treated ruby. During heat treatment routinely performed on rubies and sapphires, flux substances are commonly used to provoke recrystallization of the host corundum in fractures, and their healing leads to significant clarity improvement of the gem. Field of view 3 mm.


Finally, talking about solid inclusions, we can mention the cases when several different minerals are trapped together inside crystal as inclusions. An example could be a crystal growing in metamorphic deposit, trapping a fragment of the host rock formed by several minerals. In such cases, strictly speaking, every mineral corresponds to a different solid phase, so such inclusions cannot be considered a single phase solid inclusion. They are two-phase, three-phase or multi-phase inclusions, corresponding to the quantity of different minerals forming the included aggregate. Such inclusions are not very common and they are not separated in special classes on our website.