Powdered Mammoth Tusk

Where to find

 * Sold by Bothela of The Hag's Cure in Markarth (almost never).
 * Sold by Angeline Morrard of Angeline's Aromatics in Solitude (almost never).
 * Sold by Babette of the Dark Brotherhood (in the Dawnstar Sanctuary, almost never).
 * Note, to be able to purchase from alchemy shops you need the speech perk "Merchant" that can be acquired with a speech skill of 50 and two previous perks requiring a total of three perks.
 * Sold by Zaria of Grave Concoctions in Falkreath.
 * One is found inside your home in Markarth
 * Some may be found at the giants camp Stonehill Bluff just north of Whiterun in a stone bowl next to the bonfire.
 * Near the beginning of the first cave section of Mzulft, in an Apothecary's Satchel on a raised wooden platform by a dead Synod Researcher.
 * Drops very rarely and/or can be purchased from 'peddlers' after the world encounter including a bandit attack. This may occur more often in The Reach.
 * Sold by Arcadia of Arcadia's Cauldron in Whiterun (extremely rare).
 * One can be found in an Apothecary's Satchel on a table, in the large room inside Cragwallow Slope.
 * Can be found in an Alchemy Labratory which may be built as a north wing addition when building a Homestead using the add on Hearthfire. It comes with a lot of ingredients on the shelves including powdered mamoth tusk and pearls which are extremely hard to come by in Skyrim.
 * Chance to find one in Hob's Fall Cave inside an Apothecary's Satchel in the room where Necromancers seem to be sacrificing/resurrecting a goat.

Restore Stamina

 * Bear Claws
 * Bee
 * Charred Skeever Hide
 * Eye of Sabre Cat
 * Hawk Beak
 * Histcarp
 * Honeycomb
 * Large Antlers
 * Mudcrab Chitin
 * Netch Jelly
 * Orange Dartwing
 * Pearl
 * Pine Thrush Egg
 * Purple Mountain Flower *
 * Sabre Cat Tooth
 * Salmon Roe
 * Silverside Perch
 * Small Pearl
 * Torchbug Thorax
 * Wisp Wrappings

Fortify Sneak

 * Abecean Longfin
 * Ashen Grass Pod
 * Beehive Husk
 * Frost Mirriam
 * Hawk Feathers
 * Human Flesh
 * Purple Mountain Flower *

Weakness to Fire

 * Bleeding Crown
 * Burnt Spriggan Wood
 * Frost Salts
 * Ice Wraith Teeth
 * Juniper Berries
 * Moon Sugar

Fear
* multiple effects
 * Blue Dartwing
 * Cyrodilic Spadetail
 * Daedra Heart
 * Gleamblossom
 * Namira's Rot
 * Netch Jelly
 * Poison Bloom

Толченый бивень мамонта (Skyrim)