Calciothomsonite /Thomsonite (probably Xonotlite) (ex Pat Gross and Rich Kosnar Collections)

Item Description

This piece came to us from the Rich Kosnar collection, who acquired the piece from his mentor and New Jersey mineral collector, Pat Gross. The piece is still housed in Pat's original plastic micro mounting box, with her hand-written label attached. We've viewed and photographed the piece under the microscope, and it's very difficult to visually identify if this is Thomsonite / Calciothomsonite or the more likely species Xonotlite. According to Pete Dunn: "Thomsonite is known from Franklin and Sterling Hill, but is not found in the assemblages in which other local zeolites occur. It was first reported as calciothomsonite Gordon (1923b); this was shown to be thomsonite by Palache (1935). It was also verified from Franklin by Cook (1973). Much material labeled "thomsonite" from Franklin is in fact xonotlite, which occurs in the same assemblage, and is much more abundant. Thomsonite is a very rare mineral locally." It's our estimation that this piece is probably Xonotlite, but without Xray analysis, we can't be certain. Either way, it's a hard to find rarity with good pedigree from one of the most famous mineral producing regions in the world.