The strength and rigidity of the bone is a result of the inorganic salts deposited in the matrix. Matrix is basically just large amount of non-cellular materials, which is what your bones are made of.
The outer layer of the bone cell is very hard wich makes the bone hard.
The material of bones is hydroxyapatite.
Protein or calcium
Calcium and phosphorus.
Calcium
Osteonic canals contain blood vessels that connect to the long axis of the bone. The blood vessels that are connected perforate the canals of the bone and provide vessels to the surface of the bone which makes the bone hard.
Calcium and Phosphorus
Bone is a composite material, like fiberglass (something hard [and thus brittle] in a matrix of a more flexible substance. In fiberglass the glass makes the (fishing rod) strong, the plastic makes it tough. In bone, the calcium salts make it strong and hard, the connective tissue makes it tough.
Compact bone.
It contains calcium which is a substance that does not weight. Therefore it makes bones be strong and hard. If you took the calcium, the bones would be flexible and not hard at all.
calcium phosphate
Calcium.
Calcium
Nothing(ㅋㅋㅋ)
Calcium makes them hard.
Compact bone makes the bones hard enough so that they can provide support to the body and protect organs. It makes up the hard exterior of skeletal bones. Spongy bone (cancellous bone) is in shorter, flatter bones, and at the ends of long bones. It has more blood vessels and usually contains bone marrow, where red blood cells are produced.
Cellulose.