Kermesite

Kermesite is an unusual sulfide mineral. A close look at the formula can confirm this. There is an oxygen nested between two antimonies and two sulfurs. Kermesite, it turns out, is an intermediate oxidation product between **[|stibnite]** whose formula is **Sb2S3,** and various antimony oxides such as **[|senarmontite]**, **Sb2O3; [|valentinite],** also **Sb2O3;** and **[|stibiconite]**, **Sb3O6(OH).** Stibnite when exposed to oxygenated fluids under the right conditions will slowly transform into kermesite as the an oxygen replaces one of the sulfurs in the formula. Usually the oxidation is completed to the point that the sulfurs are completely replaced by oxygen, but in some rare cases the oxidation stops short and forms kermesite. This is fortunate for mineral collectors! Kermesite is a truly colorful mineral. Its bright red color has been described as a cherry red and that is pretty accurate. The color is caused by the stibnite and is therefore inherent in the mineral. Alternate names or nick-names for kermesite have been used such as //red antimony, purple blende// and a non-colorful nick-name //antimony blende//.

PHYSICAL CHARACTERISTICS

 * **Color** is cherry red to red.
 * **Luster** is adamantine.
 * **Transparency** crystals are translucent to rarely transparent.
 * **Crystal System** is triclinic, bar 1 (pseudo-monoclinic).
 * **Crystal Habits** include sprays or tufts of aggregated prismatic crystals and as crusts.
 * **Cleavage** is perfect in one direction.
 * **Hardness** is 1.0 - 1.5
 * **Specific Gravity** is approximately 4.5 - 4.8+ (heavy for translucent minerals)
 * **Streak** is brownish red.
 * **Associated Minerals** include **[|stibnite]** and various antimony oxides such as **[|senarmontite]**, **[|valentinite]** and **[|stibiconite]**.
 * **Notable Occurrences** include Wolfe County, Quebec, Canada; Nova Scotia; Algeria and Sonora, Mexico.
 * **Best Field Indicators** are color, luster, associations, softness and streak.