Mineral Collection of Richard Gunter

SULPHIDES

KERMESITE Sb2S2O



Location: Lac Nicolette Antimony Mine, Hamsud, Quebec, Canada

Specimen: 3 cm x 3 cm mass of porous Quartz vein material with the cavities lined with 1 mm sprays of red acicular Kermesite, 1 mm octahedrons of colourless, transparent, Senarmontite and 1 mm prisms of colourless, internally cloudy Valentinite. One of the last minerals in the vugs is 1 mm sprays of terminated secondary, metallic Stibnite. The difference between the transparent octahedral Senarmontite and the cloudy prismatic Valentinite is characteristic and is noted in the Min Record article. It is evident even in partial crystals. The Kermesite occurs as 2 to 4 mm tufts of acicular red crystals with a non-metallic lustre.

The four antimony phases: Stibnite, Kermesite, Valentinite and Senarmontite occur in equilibrium in the vug; this differs from the Frieberg Kermesite sample. This is described in both the Mineralogical Record article and the Economic Geology article. The EG article goes into more detail as to the formation of the deposit and says methane is responsible for the unusual mineralogy.

These are not alteration products of the late-stage Stibnite needles as both Kermesite and unaltered Stibnite occupy the same vug. The four antimony minerals occur as unaltered crystals apparently in equilibrium in all of the vugs on this sample. There are no powdery Sb oxides or pseudomorphs after pre-existing Stibnite, as there are on the Peretaite sample. The E-rocks website has many examples from this locality and most of the Kermesite and Valentinite samples occur as microcrystals in porous vein centers. No complete section of the vein with both walls has been documented so the veins centers were largely open and porous with no strength to hold the samples together. Massive tin-white Native Antimony occurs in the Quartz vein that is the matrix of the sample. Gudmundite, Native Antimony and Stibnite were the ore minerals in the mine. The powdery light tan coloured coating on some surfaces is fine-grained Senarmontite.

Locality Library: Lac Nicollete; a classic Canadian locality for antimony minerals. An article in the Mineralogical Record in 1983 outlines the deposit and describes the minerals associated. These vugs occur in the centre of the veins and are not directly related to a weathering horizon. There are three phases of Stibnite and two of Kermesite in the EG paragenetic chart. A 1996 Economic Geology article on the deposit is in the computer. It is later than the Min Record article and contains more details on the structure of the antimony veins that make up the deposit and more details of its chemistry; there is less on the mineral descriptions.

The presence of the four antimony minerals in equilibrium must have been the result of unusual conditions in the vein and the both the Mineralogical Record and EG articles discuss the conditions of formation. This does not appear to be the result of weathering of a Sb deposit but is the result of hydrothermal and Ph/eH reactions of Native Antimony and Stibnite. There are two types of antimony veins at the locality of which the K-S-V veins were one type. The other type contains Albite and Gudmundite. The Pezinok, Slovakia, Kermesite deposit has been written up in the Min. Record. It also contains hydrothermal Kermesite and Valentinite.

I purchased the sample at the April 8th, 2017 Abbotsford show from John Dagenais as: Stibnite, Kermesite, Senarmontite, & Valentinite, Lac Nicolette Antimony Mine, Hamsud, Quebec, Canada. The locality card does not have his designation so he did not collect this sample.