Short answers, pulled from the story.
10 Hygiea was discovered on the 12th of April 1849 by Italian astronomer Annibale de Gasparis at the Astronomical Observatory of Capodimonte in Naples, Italy. It was the tenth asteroid discovered in history and the first found by de Gasparis.
10 Hygiea is the fourth-largest main-belt asteroid by both volume and mass, with a mean diameter of 433 kilometers. Its mass constitutes 3 percent of the total mass of the main asteroid belt. Compared to Ceres, the largest asteroid, Hygiea is less than half its diameter and roughly 10 percent as massive.
Since 2019, telescope images have resolved Hygiea's nearly spherical shape, suggesting it may have reached hydrostatic equilibrium, one of the criteria for dwarf planet status. Hygiea already orbits the Sun and appears spherical, but it has not cleared its orbital neighborhood. The IAU has not yet officially classified Hygiea as a dwarf planet.
The Hygiea family, comprising over 7,000 known asteroids, is believed to have formed by a giant impact on Hygiea about 2 to 3 billion years ago. The collision ejected at least 1.7 percent of Hygiea's original mass and is thought to have completely shattered the body, which then reaccumulated under gravity into its current nearly spherical shape.
Hygiea has a dark, carbonaceous surface composed largely of hydrated and ammoniated silicate minerals, carbonates, and traces of water ice. James Webb Space Telescope observations identified its phyllosilicates as magnesium-rich ammoniated saponite. Its spectrum closely resembles that of Ceres and carbonaceous chondrite meteorites.
Hygiea was named after Hygieia, the Greek goddess of health and daughter of Asclepius. The name was proposed by Ernesto Capocci Belmonte, director of the Capodimonte Observatory, at the invitation of discoverer Annibale de Gasparis. The original proposed name was Igea Borbonica, honoring King Ferdinand II of Naples, but the Borbonica portion had been dropped by 1852.