What does "worried stone" mean in this poem from "Tumor"?

Question

In "Tumor", by Anna Leahy, the author wrote a poem about her mother's cancer death, with the title "Gravity 2", after she had written a poem about her father's death, with the title "Gravity 1":

She falls with the weight of herself
and her unsteady state, a state of un-being.
A moment arrives when my mother can no longer hold up.
When gravity overcomes pressure,
the lungs can’t draw another breath.
The memory I have of my mother
glows like a white dwarf. She sometimes eludes
my mind’s eye, but even a worried stone
dropped from my extended hand to my heart
is so heavy, it travels thousands of miles an hour.

What does "worried stone" mean in this context?

Answer 1

The poem consists of two conceits (extended metaphors) on the subject of gravity, as suggested by the title.

In the first conceit, gravity is a metaphor for death: the speaker’s mother is being pulled downwards by gravity (that is, towards her grave) until she can no longer hold herself up (that is, she dies). There is an etymological connection: “gravity” derives from “grave” meaning “place of burial”.

In the second conceit, gravity is a metaphor for grief. The speaker’s memory of her mother is “like a white dwarf”, which rapidly accelerates a “worried stone” dropped from her outstretched hand. A white dwarf is a small and very dense star with a high surface gravity that is formed when “gravity overcomes pressure” in a star and it collapses. As pointed out by Peter Shor in comments, a worry stone is a smooth stone that is “worried” (rubbed) to relieve anxiety and stress. Alternatively, “worried” is a transferred epithet: it is the speaker who is “worried” (afflicted with grief). As in the first conceit, there is an etymological connection: “gravity” is related to “grieve”, which formerly meant “to press heavily upon, as a weight” (OED).