After great pain, a formal feeling comes – The Nerves sit ceremonious, like Tombs – (1-2)
The words "ceremonious" and "Tombs" evoke the idea of a funeral and give us the feeling of what it's like to feel dead while we're still alive. When we're sitting around depressed at a funeral, we can definitely feel that way. Notice that the speaker describes something that's part of a living body—"the Nerves"—in these funereal terms. At first this contradiction may not line up in our head, but when we think about it for a sec, we see how it captures that dead-alive feeling perfectly.
A Quartz contentment, like a stone – (9)
This one might not be the most obvious reference to death, but the image seems a little death-y to us. What could be more content than a stone? And when are we more content than when we're dead? This line also reminds us of the "Tombs" back in line 2, even though we've never seen a gravestone made of quartz. Why do you think the speaker chooses to reference quartz specifically here? What's significant about this particular type of stone?
This is the Hour of Lead – Remembered, if outlived, As Freezing persons, recollect the Snow – First – Chill – then Stupor – then the letting go – (10-13)
It's weird that the poem references people who have died from freezing to death as being able to remember the snow that killed them. Kind of hard to remember stuff when you're dead, right? Here's another way of looking at it, though: what if "the letting go" is meant to represent the moment in which we finally get over a trauma? Though it's the death of one part of our lives, it's also the birth of another.