Both amalgam and cinnabar are mercury-containing substances. Amalgam is a metal alloy while cinnabar is a mineral substance.
What is Amalgam?
Amalgam is an alloy of mercury with another metal. With the exception of iron, platinum, tungsten, and tantalum, any other metal can be used along with mercury in the preparation of amalgam. Amalgam can be prepared as a liquid, as a soft paste, or in the form of a solid. This phase of amalgam differs according to the proportion of mercury used during the preparation. The alloy is formed though metallic bonds that are electrostatic attraction forces between the conductive electrons of metal atoms; the conductive electrons tend to bind all the positively charged metal ions together into a crystal lattice structure. The most important amalgams include the combination of mercury with silver and gold. Silver-mercury amalgam is used in dentistry while gold-mercury amalgam is important in extracting gold from gold ore.
When considering the toxicity level of amalgam, dental amalgam is considered to be safe for human. However, in 2018, the use of dental amalgam for children under 15 years and for pregnant mothers and breastfeeding women was prohibited.
What is Cinnabar?
Cinnabar is a mineral containing mercury(II) sulfide. This mineral has a brick-red appearance, and it is the most common ore for the refining of elemental mercury. It is also the source for the brilliant red or scarlet pigment called vermilion. Generally, this mineral occurs as a vein-filling mineral associated with recent volcanic activity and alkaline hot springs. In its appearance, cinnabar resembles mineral quartz.
When considering the mineral properties of cinnabar, it has a rhombohedral crystal habit, prismatic but perfect cleavage, uneven subconchoidal fracture, 2.0 Mohs scale hardness, dull lustre, and scarlet streak colour. In thin pieces, the mineral is transparent.
Generally, cinnabar occurs in massive, granular or earthy form. Occasionally, it occurs in crystal form with nonmetallic adamantine lustre. Structurally, the cinnabar mineral is categorized under the class of trigonal crystal system.
We can use cinnabar to obtain liquid mercury by crushing the mineral and roasting it in rotary furnaces. Furthermore, pure mercury is separated from sulfur in this process, and mercury is easily evaporated. Thereafter, we can use a condensing column in order to collect the liquid metal, and this liquid form (also called quicksilver) is transported in iron flasks.
There are different uses of cinnabar, mainly in decorative purposes due to its colour. The most common use for cinnabar is in Chinese carved lacquerware production. Furthermore, there are different other types of cinnabar, such as hepatic cinnabar or paragite, hypercinnabar, metacinnabar, and synthetic cinnabar.
What is the Difference Between Amalgam and Cinnabar?
Amalgam and cinnabar are mercury-containing substances. The key difference between amalgam and cinnabar is that the amalgam is an alloy of mercury, whereas the cinnabar is a mineral containing mercury(II) sulfide. Moreover, amalgam has a shiny and lustrous appearance while cinnabar has a brick-red colour.
The following infographic presents more differences between amalgam and cinnabar in tabular form.
Summary – Amalgam vs Cinnabar
Amalgam and cinnabar are mercury-containing substances. The key difference between amalgam and cinnabar is that amalgam is an alloy of mercury, whereas cinnabar is a mineral containing mercury(II) sulfide.
1.“Cinnabar.” Geology, Available here.