Pääkkönenite is a metallic grey mineral with the molecular formula Sb2AsS2. It is named after Veikko Pääkkönen (1907–1980), a Finnish geologist. It is a fairly rare mineral, and some specimens were discovered in association with the spectacular new kermesites (2002) from China.
General Information
It is silvery-gray metallic, elongated but platy, crystals in spherical aggregates associated with dolomite and kermesite. The identification of this mineral has been confirmed by single-crystal X-ray diffraction.
- Category: Sulfide minerals
- Formula: Sb2AsS2
- Crystal system: Monoclinic
- Crystal class: Prismatic (2/m)
- Color: Grey
Properties
- Tenacity: Brittle
- Mohs scale hardness: 2.5
- Luster: Metallic
- Streak: Grey with brownish tint
- Diaphaneity: Opaque
Occurrence: In hydrothermal mineral deposits with other Sb–As-bearing minerals.
This locality is better known for the large world-class kermesite crystals that it has produced than its pääkkönenite specimens. So far it would appear that the pääkköneite has been recognized on only a few specimens of well-crystallized stibnite and kermesite from the locality. The specimen was trimmed a little to make it more saleable before it was known that the specimen contained the rare mineral. The original specimen on which this new find was discovered was on a crust were well crystallized stibnite and kermesite were associated with sharp micro crystals of yellow valentinite.
Association: Arsenopyrite, arsenic, l¨ollingite, stibnite, antimony (Kalliosalo deposit, Finland); stibarsen, arsenic, stibnite, sphalerite, siderite, quartz (Pˇr´ıbram, Czech Republic); vaughanite, stibarsen, realgar, arsenic (Hemlo mine, Canada).
