I was watching the television series “The Mystery at Blind Frog Ranch”, season 2 episode 5 on Discovery, when they came across some rocks that had been drilled and gallium placed in the voids. The rocks were then crated and hidden in a cave system. I wanted to research the gallium for myself.
Gallium is considered a post-transition metal. Physically, post-transition metals are soft (or brittle), have poor mechanical strength, and have melting points lower than those of the transition metals; most also have boiling points lower than those of the transition metals. Usually included in this category are Gallium, Indium, Thallium, Tin, Lead, and Bismuth.
The Solid gallium is of blue-gray metal having an orthorhombic crystalline structure, constituting a system of crystallization characterized by three unequal axes at right angles to each other, whereas very pure gallium is coated with stunning silvery color.
It does not exist in pure form in nature, and its compounds do not act as a primary source of extraction. It is used in Blue-ray technology, blue and green LEDs, mobile phones, and pressure sensors for touch switches. Gallium nitride acts as a semiconductor. It consists of certain properties that make it very versatile.
This metal can be easily extracted as a by-product from iron pyrites, zinc blende, germanite, and bauxite. It is solid at room temperature but when it comes in contact with cesium, mercury, and rubidium it becomes liquid (when heated slightly). This element has been considered as a possible heat exchange medium in nuclear reactors.
When Gallium is added to certain metals it causes them to become brittle. Gallium has one of the largest ranges in which it is a liquid when compared to other metals.
In 1871, the existence of gallium was first predicted by Russian chemist Dmitri Mendeleev, who named it “eka-aluminum” from its position in his periodic table. He also predicted several properties of eka-aluminum that correspond closely to the real properties of gallium, such as its density, melting point, oxide character, and bonding in chloride. Gallium does not exist as a free element in the Earth’s crust, and the few high-content minerals, such as gallite (CuGaS2), are too rare to serve as a primary source.
Gallium is also used for neutrino detection. Possibly the largest amount of pure gallium ever collected in a single spot is the Gallium-Germanium Neutrino Telescope used by the SAGE experiment at the Baksan Neutrino Observatory in Russia. This detector contains 55–57 tonnes of liquid gallium.