Limestones. The most common chemical sedimentary rock is limestone. Composed mostly of the mineral calcite (CaCO3), limestones are usually formed by biochemical processes in shallow seawater.

Since ions can stay in solution for tens of thousands of years (some much longer), and can travel for tens of thousands of kilometres, it is virtually impossible to relate chemical sediments back to their source rocks. The most common chemical sedimentary rock, by far, is limestone.

Unlike most other sedimentary rocks, chemical rocks are not made of pieces of sediment. Instead, they have mineral crystals made from elements that are dissolved in water. The water in the oceans, lakes, and ground is often full of dissolved elements. All sorts of things can dissolve into water.

The lack of nearby erosion explains the high purity of chalk. The coccolithophores, foraminifera, and other microscopic organisms from which the chalk came mostly form low-magnesium calcite skeletons, so the sediments were already in the form of highly stable low-magnesium calcite when deposited.

Calcium carbonate and calcium citrate are the two most recommended forms of calcium supplements. Calcium carbonate is cheaper and more common. It can be found in most antacid medicines. It needs to be taken with food in order for it to work well.

After analyzing 10 years of medical tests on more than 2,700 people in a federally funded heart disease study, researchers at Johns Hopkins Medicine and elsewhere conclude that taking calcium in the form of supplements may raise the risk of plaque buildup in arteries and heart damage, although a diet high in calcium- …

The two main forms of calcium supplements are carbonate and citrate. Calcium carbonate is cheapest and therefore often a good first choice. Other forms of calcium in supplements include gluconate and lactate. In addition, some calcium supplements are combined with vitamins and other minerals.

Calcium is absorbed best when taken in amounts of 500 – 600 mg or less. This is the case for both foods and supplements. Try to get your calcium-rich foods and/or supplements in small amounts throughout the day, preferably with a meal.

The two most commonly used calcium products are calcium carbonate and calcium citrate. Calcium carbonate supplements dissolve better in an acid environment, so they should be taken with a meal. Calcium citrate supplements can be taken any time because they do not need acid to dissolve.

Vitamin D Recommendations According to the report, children older than 1 years old and adults up to 70 years of age are recommended to consume 600 IU of vitamin D daily and adults greater than 70 years of age are recommended to consume 800 IU of vitamin D daily [40].