inclusions in Quartz egg
Mineral Inclusions by Marilyn Ginsburg ,member of the Gem and Mineral Club of Scarborough
Minerals with inclusions in them are some of the most interesting and beautiful specimens to collect. These inclusions can be made up of other crystals trapped in liquids or gases or foreign particles that coat the faces of the crystals as they are developing.
Some inclusions are formed earlier than the host mineral and some are formed at the same time. The long slender golden crystals of rutile that are seen in some of these crystals formed first, and were later covered by the host mineral, quartz. Quartz is a mineral that often crystalizes last, thereby enclosing earlier formed species, such as epidote , tourmaline, pyrite and zeolite minerals.
Rutile crystals in quartz
Graceful veins and wasps are often tiny cavities in the crystal which contain liquids and gases. These could have been droplettes which were stuck into the growing crystal faces and were then covered by the growing qusrtrz. Sometimes fibreous minerals ,such as asbestos, can be trapped in the quartz, creating beautiful white swirls.
Sand calcite crystals can have more of the included mineral, sand, than calcite that cements it all together.
The sprinkling of foreign material on the host crystal during its growth results in thin coatings which then become inclusions. If these coatings are repeated and are spearated by time intervals,the crystal will display a number of “phantom” crystals,which represent the size and shape of the crystal when it was younger. These phantoms are among the most fascenating of mineral inclusions.
Selenite crystal with inclusions
Some mineral specimens with inclusions must be cut and polished to reveal the hidden treasures inside
Come to the club’s annual show ,September 17,18 to see more examples of minerals with inclusions that reveal their past history.
