Sulfur is bright yellow. The color may be altered if impurities are present. Clay and selenium impurities
, as well as volcanic mixtures in sulfur can cause it to be slightly red, green, brown, or gray. Sulfur often occurs in petroleum deposit
s, where it is found coated with greasy black petroleum.
Sulfur is soft, light in weight, and very brittle
. Care must be exercised when handling and storing specimens. When kept moist or not allowed to dry when wet, hydrogen will mix with the Sulfur, forming hydrogen sulfide (H2
S), which causes the deterioration of a specimen. To prevent this, Sulfur should not be stored under humid conditions. It is best not to wash Sulfur specimens, as warm water can dissolve them. Sulfur also has the tendency to crack when exposed to mild heat, including body heat. It should be handled as little as possible, and kept out of light to avoid cracking.
, specimens usually come from volcanic
sulfur springs, and have small, bubbly holes throughout. These specimens usually have a greasy feel, and exhibit a strong "rotten-egg" odor.
Much of the fine natural Sulfur crystals are destroyed by mining
operations. In mining, underground Sulfur deposits are flooded with hot water, causing the Sulfur to melt into a brine
. The brine is pumped to the surface, where the water is evaporated and the sulfur recovered. Such mining operations destroy all specimens.
Sulfur crystallizes in the orthorhombic
system, but an uncommon monoclinic
form of sulfur also exists. This monoclinic form is scientifically considered a different mineral than Sulfur, and is scientific name is Rosickyite