Above the core is Earth’s mantle, which is made up of rock containing silicon, iron, magnesium, aluminum, oxygen and other minerals. The rocky surface layer of Earth, called the crust, is made up of mostly oxygen, silicon, aluminum, iron, calcium, sodium, potassium and magnesium. These materials change over millions of years. Igneous rocks make up over 90% of the Earth’s crust by volume. A single family of silicates, the feldspars, account for about half of the material in the crust (60% by weight). and quartz is a sizeable proportion of the rest. Other common minerals are mica and hornblende. Time has shaped these stones into what we see as beautiful hearts. They can be used for healing, meditation, affirmations, jewelry, photography, crafts and more. Here are a few places you can find out more about heart stones and their powers. www.crystalsrocksandgems.com http://heartrocks.blogspot.com/ http://kidsactivitiesblog.com/24810/share-the-love http://www.josieiselin.com/ http://www.heartstones.com/
