US poet Ruth Stone, whose career flourished in her 80s and 90s, has died in Vermont at the age of 96.Her 1959 debut, In an Iridescent Time, was followed by 1971's Topography and Other Poems, and 1986's American Milk.Her best-known work, including The Solution and Simplicity, came after she turned 70. In 2002, she won the National Book Award for Poetry, for In the Next Galaxy.She received acclaim for her insights into love, death and nature.Her second husband, poet Walter Stone, took his own life in 1959 - the year of her debut - leaving her to bring up three daughters.In her poem All Time is Past Time, she writes: "Actually the widow thinks, he may be, in another country in disguise."And in The Widow's Song, she asks: "If he saw her now, would he marry her? The widow pinches her fat, on her abdomen."Other honours included a National Book Critics Circle award, two Guggenheim Fellowships and a Whiting Award. She was named as a Pulitzer Prize finalist in 2009 for What Love Comes To.In the Next Galaxy, the volume of poetry which won her the National Book Award, is "a collection of sardonic, crafty poems" questioning the role of convention in everyday life.Stone died of natural causes at her home in Ripton surrounded by family, her daughter Phoebe said.