Question

Chemical formula of ruby silver is:
(A) $A{{g}_{2}}S$
(B) $AgCl$
(C) $AgN{{O}_{3}}$
(D) $A{{g}_{2}}S.S{{b}_{2}}{{S}_{3}}$

Answer 1

Hint: The correct option is a sulfosalt mineral. This mineral is known as pyrargyrite and has a trigonal crystal system. The mineral is also known as a dark red silver ore and is an important source for the metal.

Complete step by step solution:
-Ruby silver is also known as Pyrargyrite. It is an interesting mineral which contains silver in its chemical structure. Pyrargyrite is one among the few silver-bearing minerals which can exhibit transparency.
-This mineral also contains two very distinct habits one as transparent, deep-red crystals, and the other in opaque, dark-metallic grey form. A number of the metallic-looking and opaque specimens will still exhibit slight red colour and transparency when backlit.
-Ruby silver is light sensitive. When the mineral is subjected to prolonged exposure to bright light then it will darken its transparency and cause it to become darker. This prolonged exposure of ruby silver may also cause a dull, dark film to form on crystal faces and usually, this film is removed by brushing a specimen with water and soap.
-Let's look at the chemical composition of ruby silver. The chemical formula for ruby silver is $A{{g}_{2}}S.S{{b}_{2}}{{S}_{3}}$. As we can see it’s a silver antimony sulfide and also a sulfosalt mineral. The percentage composition for ruby silver can be given as $59.76$ for silver, $22.48$ for antimony and $17.76$ for Sulphur.

Therefore, the correct answer is option (D). $A{{g}_{2}}S.S{{b}_{2}}{{S}_{3}}$.

Note: There might be confusion among the options. $AgCl$ is known as horn silver and $A{{g}_{2}}S$ is silver sulphide and $AgN{{O}_{3}}$ is silver nitrate. Also, it should be noted that the mineral Pyrargyrite is very similar to Proustite which is an arsenic-rich member instead of antimony in pyrargyrite and it's also known as light red silver ore.