5/6/23: The final rocks have been taken from this geocache (despite explicit instructions not to take the final rock from any of the caches in this series); there are unfortunately no more rocks to see here. You can see pictures of the original contents of this cache, and read more about the rocks, below. Tradeables are now permitted in this cache.
During the great quarantine clean of 2020, I discovered my rock collection, assembled over years of studying geology in college and just picking up cool rocks along the way. Having way more rocks than we knew what to do with, we thought it would be fun to share them with fellow geocachers in a new series along the Merrimack River: the rock collection! These 15 caches are hidden in a linear fashion along a portion of the Bay Circuit Trail which can be walked or biked, across AVIS's Deer Jump Reservation (and a couple other reservations as well). The containers vary in size, but each should be an easy find. Each one highlights a different really cool rock. Tradeables may not be left in these caches, though if you collect rocks yourself you can keep a rock from some (but not all) of these caches. Coordinates for a possible trailhead are provided, though there are many places you could begin your hike.
Palladium Core and Ultramafic Rocks
During a geology field trip in college I was lucky enough to get to visit the Stillwater Mine in Montana, the only location where Palladium exists in the United States. Palladium is a rare metal element that only exists in a few places around the world. It is used in Catalytic Converters (exhaust control devices on vehicles) and in many electronic circuits, and along with Gold, Silver, and Platinum, is one of the four most valuable metals in the world. While at the mine, we were given samples of palladium cores, bits of rock that the mining company drilled from the earth to test if more extensive mining would be useful in an area. I can't imagine that the rock in this geocache has anything more than trace amounts of Palladium, but it's still interesting to see. (For any Marvel fans out there, Palladium is also the element that Tony Stark uses in his arc reactor to power his Iron Man suit in the first Iron Man movie.)
This cache also contains a few ultramafic rocks collected around the outside of the mine. Ultramafic rocks are low in silica content and often high in metal content, are often darker in color, and can be found deep in the earth's mantle below the crust. The area around the mine was unique because, after lots of erosion and uplife, the ultramafic rocks ended up on the surface. The rock at the top of the photo is the palladium core; the other three rock are ultramafic rocks.
