A silver hourglass denotes the second 10 years of service and a gold hourglass, the third 10-year period. Guard and reserve members who complete 40 years of reserve service will now wear both gold and bronze hourglasses on the Armed Forces Reserve Medal. The revised manual is expected out soon. Calcium is the most abundant mineral in the human body. About 99 percent of the body's calcium is in the bones, and the rest is in the soft tissues.
Most people know that calcium is needed for building and maintaining bones and teeth.
Whew, that's a lot of work for a little mineral. The calcium that does all this work circulates in the blood, and the body regulates the level of blood calcium very carefully. Extra calcium is stored in the bones, where it can be released quickly if the levels of calcium in the blood drops too low. Despite its importance, calcium is available in significant amounts from very few foods. Most people think of dairy products as sources of calcium.