Please don't take any rocks from this cache as the rocks are helping to hide the container!
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.
Pyrite
Pyrite, commonly called "fools gold", is a blocky metallic-looking crystal formed in rocks high in iron content. It is formed when sulpher disolved in water is carried into these rocks through cracks and pores. The sulpher then bonds with the iron creating the mineral pyrite which is commonly mistaken for gold. These rocks were found on Henderson Mountain in Montana, the site of a number of old gold, silver, lead, zinc, and copper mines. We visited Henderson Mountain on a geology field trip, where our assignment was to climb all over the mountain and map any fault lines and fractures we could find. The presence of pyrite often indicated a fracture, as this was where water had an opportunity to flow into the rock, carrying the ions necessary to cause iron to precipitate out of the iron ore.
Find the pyrite, and you'll find the cache! The rocks at this cache don't only contain pyrite; there are a number of other metallic-looking, iron-rich minerals in the rocks as well. Also, one of the rocks at this cache contains a small natural geode!