Cairns and small chambers in Washington MA, from Norman Muller

Last year around this time, I spent a day exploring parts of Washington, MA, with a former NEARA member, who has spent years exploring this part of the state. Following is a selection of the features we saw that day.
In the morning, I was taken to a side street out of town, where I was shown a very small chamber built into a slope -- certainly too small for a person. On top of the lintel, in the center, was a piece of hematite, which is pure iron oxide and very heavy. Was this placement purely accidental? I don’t think so. Hematite is a source of red ochre, which is often associated with ancient burials.

Later that morning, I was shown a huge cone cairn, probably 7’ high, in the middle of a trail.
At the base, on one side, was a tiny chamber, and it was topped with a piece of quartz. I had seen a chamber built into a wall before (at Scotrun, PA), but never an obvious chamber in a cairn. [Reverse view:]

In the afternoon we visited a cairn site on a ridge outside of town. It was the high point of the trip, and rather overwhelming. There were several large platform cairns (two are shown), one of which had a long “pointer” stone row below it. This was a new element for me.
Then there were a number of very elaborate cairns on boulders, one of which had at its base a small above-ground chamber. [A closeup of the cairn is also shown] This reminded me somewhat of the chambers I saw in Hopkinton, RI, in a middle of a boulder field. Since they were in an area of underground springs, which were audible in places, I concluded that the small chambers were built over locations where the sound of the springs was strongest. But the one in Washington is in a different class altogether, and I am not sure what to make of it. I am convinced, however, that it is related to all the other stonework around.

Lastly, was a very nice boulder fill, of a type that I have seen numerous times, but not like this.