This poem actually seems to capture a very specific stage of grief that comes after the initial shock of finding out about the disaster or tragedy and before the dealing with it and moving on with life. Dickinson describes this middle stage as being like "a formal feeling," and further goes on to describe it as "the hour of lead," perhaps using this to consolidate earlier descriptions of how the body, going through this stage of grief, adopts a kind of woodeness in its movement. The diction used in this poem seems to capture the way in which the body becomes hardened and numb. Consider the use of words such as "lead" and "quartz." The next stage, after the initial shock, is a gradual hardening as the reality of the loss becomes clear to the suffering individual.
However, it is the final line of the poem that places this stage of grief in its overall context. Note how Dickinson uses an image of a freezing person remembering the snow to describe how grief operates:
As freezing persons recollect the snow--
First chill, then stupor, then the letting go.
Coping with grief therefore involves the first shocking "chill" of loss, then the gradual "stupor" that this poem focuses on before the final "letting go" of that grief and the way that we carry on with our lives.