Physical Properties of Arsenic

It is known that arsenic used to be utilized in ancient times and that it was dangerous but the symptoms for the poisoning of arsenic were not well defined and because of this it was often times used for committing murders that is until the beginning of the Marsh test. The Marsh test is a very sensitive method in the recognition of arsenic and is very useful in the field of forensic toxicology when arsenic used to be utilized as a poison. It was developed by the chemist James Marsh and was first published 1836. Arsenic, in the form of white arsenic trioxide used to be utilized a great deal as a poison because it did not have any odor and was easy to place inside food and drink and prior to the advent of the Marsh test, could not be traced in the human body. Recently there have been some fatal animal poisonings due to arsenic as well as some human fatalities because of the ingestion of ash wood directly or indirectly from copper arsenate timber. Arsenic is known to be a chemical element in the periodic table and has an atomic number of 33. It is a very poisonous metalloid and has three allotropic forms which are yellow, grey and black and is somewhat alike phosphorous. Arsenic will oxidize to arsenic trioxide when it is heated quickly and will take on the smell of garlic. Arsenic along with some of the compounds in addition sublimes and turns into a gaseous form. Elemental arsenic takes place in two forms of solid and has a yellow and grayish-metallic color; however they do not always form in their elemental state. This is more often times seen in sulfides and sulfosalts such as realgar, orpiment, arsenopyrite, tennantite and lollingiten. The arsenic ores that exist have an abundant amount of arsenic but native arsenic is not common, and because of this it is considered an important ore on its own. Native arsenic can be found in silver ore veins and is processed with the silver ore as well and this will form a little source of arsenic. The minerals that are associated with arsenic include: silver, barite, dyscrasite, nickeline, and cinnabar. The occurrences of arsenic can be found in the United States, Italy, France, Norway, Germany, Japan, and England.  

The physical properties of arsenic

• Color: white that will easily become tarnished to a dark grey to black
• Luster: metallic however the tarnish will usually dull the luster a great deal
• Transparency: crystals that are opaque
• Cleavage: basal in one direction however this commonly cannot be seen
• Fracture: uneven
• Hardness: 3 to 4
• Specific gravity: 5.4 to 5.9 +
• Streak: black