Final answer:
Bones consist mainly of bone tissue, which is a type of connective tissue mineralized with calcium and phosphorus crystals.
Step-by-step explanation:
Bones are organs that consist mainly of bone, or osseous, tissue. Osseous tissue is a type of connective tissue consisting of a collagen matrix that is mineralized with calcium and phosphorus crystals. The combination of flexible collagen and minerals makes bone hard without making it brittle.