when a wizard is expelled from Hogwarts, their wands are snapped in half. This type of damage to a wand is nearly irreparable, though Harry is able to mend his wand, which was accidentally broken by Hermione, with the help of the powerful Elder Wand. A wand is made by a wandmaker who is learned in wandlore, the study of wands. Wands are handcrafted from high-quality woods, or "wandwoods", which are capable of sustaining magic (e.g. holly, yew, ebony, vinewood, mahogany, cherry, oak, etc.). A core is then inserted into the middle of the wand from top to bottom, which gives it its power to generate magical effects. Common cores include phoenix tail feathers, unicorn tail hairs, and dragon heartstrings. Veela hair is also used, but less commonly. In the Deathly Hallows, the Elder Wand is described as the only wand with a core made from the tail hair of a Thestral. The only wand shop seen in the books is Ollivanders. Garrick Ollivander is a wandmaker who has an eidetic memory concerning wands, as well as the ability to identify the distinguishing features of a wand. In Harry Potter and the Goblet of Fire, Ollivander is seen to evaluate two foreign wands: Viktor Krum's, whose wand was crafted by Gregorovitch, was unusually thick and had a dragon's heartstring core; Fleur Delacour's, created by an unknown wandmaker, was made of rosewood with a core of Veela hair. Ollivander believes Veela hair produces "temperamental" wands and does not use it. Salazar Slytherin's wand contained a fragment of a basilisk horn, which allowed Slytherin and other Parselmouths who possessed it to cast spells with it at a distance by speaking to it in Parseltongue. In the United States, wand cores are created from the horn of river serpents, Wampus hair, Snallygaster heartstring, and Jackalope antlers, a practice originated in the 17th century by the first American wandmaker, Isolt Sayre, an Irish immigrant who founded the Ilvermorny School of Witchcraft and Wizardry in Massachusetts, and the Slytherin wand's last owner. She buried it outside the school grounds, and within a year, an unknown species of snakewood tree grew from the burial spot. It resisted all attempts to prune or kill it, but after several years the leaves were found to contain powerful medicinal properties. A wand is generally considered a very personal object. Wands belonging to other wizards can be borrowed, resulting in