The Erickson Athletic Complex, half a mile northeast of the main Brown University campus, is partially encircled by a stone wall "six thousand two hundred and twenty and one-half feet" long originally built around a "poor farm for indigent freemen" in 1835. Many of the stones comprising this wall are glacial erratics transported by ice from elsewhere in Rhode Island or Massachusetts. The stone wall is an excellent open-air museum. There are several very good specimens of cumberlandite (far better than what remains to be collected at Iron Mine Hill) in the wall segment along Hope Street between Cushing and Bowen Streets, along Arlington Avenue, and at the end of Diman Place. There are many other interesting rocks in the wall, some of which are pictured below. Thanks to cumberlandite researcher Judy Hadley for suggesting this location to me.

Cumberlandite
Cumberlandite. Note oriented white plagioclase crystal aggregates.

Leucogabbro
Cumberlandite's complementary leucogabbro

Quartz
Chunk of vein quartz from Diamond Hill?