I listened on YouTube to two major chamber works by Amy Beach, these on Chandos and licensed by Naxos, by the Ambache ensemble.
One is the Piano Quintet in F# Minor, Op 67, about 27 minutes (1907). The work is later than the Piano Concerto and Symphony, but the idiom is still largely post-Brahmsian. The work has a lot of varying tempi actually recalls Brahms Piano Sonata #2 to my ear (in the same key). The first movement, in contradiction to her earlier big works, slows down to a quiet ending in minor. The second movement is a song in the dominant major, here D-flat. But at the very end of the Finale, it’s all joyful.
The Piano Trio in A Minor, Op 150 (1939), is in three short movements, and the first movement, over a waltz rhythm, explores some impressionistic, perhaps a bit Scriabin-like, dissonances and chords. The slow movement is a song without words in F#, and the Finale will sound a little more familiar, with a Dvorak-like lilt and a happy ending in A Major.