Animal, plant and synthetic fibers are all used to make yarn....wonderful yarn!
a) Types and Characteristics of Yarn
Wool: (A Natural Yarn) comes from sheep, great for felting.
Some different types of wool include
Lamb's wool: comes from a lamb's first shearing
Merino Wool: Comes from the finest of the fine breeds
Pure New Wool or Virgin Wool: Comes directly from the sheep and not recycled from wool garments.
Washable Wool: a treated wool that will not felt
I believe a wool yarn or garment needs to have a content of more than 50% wool to be considered feltable.
Mohair: Comes from the Angora goats
Cashmere: Comes from the kashmir goats
Angora: Comes from Angora rabbits
Silk: Soft, shiny fibers the come from the Silkworms cocoon
Cotton: A soft white, natural fiber from the cotton plant
Bamboo: A very soft, slippery and shiny plant based yarn.
Corn: Plant based yarn, similar to cotton.
Soy: Plant based yarn, lustrous like silk.
Linen: Made from flax, a natural plant fiber
Lyocell (Tencel) and Rayon: A man-made yarn that is produced from cellulose, a natural material.
Nylon: A synthetic yarn known for great strength and elasticity
Acrylic: A synthetic yarn that is made to look like and mimic natural yarns.
Novelty yarns: Novelty yarns can be made from any fiber but are easily recognizable because there are so different from normal yarns. Some examples include Ribbon, Boucle (a very bumpy yarn composed of loops), Chenille, thick and thin(slub), railroad ribbon and eyelash.
Tweed: Has a main color flecked with different colors
Heathers: Blended yarn
Marled (ragg): a plied yarn, where plies of different colors are spun together.
Variegated: A yarn dyed in several different colors
Characteristics of yarn
Absorbency: The ability of a fiber to absorb and hold in water.
Breathability: The ability of a fiber to allow air flow between it.
Dyeablility: The ability of a yarn to take and hold dye.
Loft: The amount of air between fibers.
Resiliency (elasticity): The ability of a yarn to return to it's state after behind stretched and pulled.
Drape: how the yarn hangs, how stiff or supple is it?
If you are just learning to crochet, choose a non-fuzzy, light colored, that doesn't unravel easily. This will make learning much easier and remove some possible frustration.
b) Yarn Weight with recommended hook sizes