Feldspars are members of a mineral group that contains at least twenty (some sources say forty) different aluminum silicate minerals and makes up 50% - 60% of the Earth's crust. The minerals grouped together as Feldspars contain varying amounts of sodium, potassium and calcium but all of them have similar atomic structures and therefore similar characteristics and physical properties. Feldspars commonly occur in igneous rock, but are found in many environments. The US Geological Survey says that in America Feldspar is found "in igneous, metamorphic and sedimentary deposits from coast to coast and border to border" (USGS) and the same is true around the world. Despite being so common it is rare for Feldspars to occur as gemstones, though some varieties of the mineral, such as Moonstone and Labradorite, have a beautiful irridescence caused by light being scattered between fine layers of crystals in what is known as the 'Schiller Effect', from an old German word that means 'to twinkle'.
Feldspar, sometimes called Feldspat, comes from the German terms 'Feld' (field), referring to the mineral's abundance and the fact that as it breaks up it becomes a major component of soil, and either 'spar' (a term for a rock that splits easily) or 'spat' (a term for a rock that does not contain ore). It is also sometimes known as Rhombic Quartz. Because the Feldspars are light, low density silicate minerals they can float in magma and therefore tend to accumulate closer to the surface of the planet than denser minerals.
The Feldspar group includes Plagioclase Feldspars (Albite, Oligoclase, Andesine, Labradorite, Bytownite, Anorthite) and Alkali or K Feldspars (Microcline, Sanidine, Orthoclase, Anorthoclase) as well as Amazonite, Moonstone, Sunstone, Celsian, Paracelsian, Hyalophane, Perthite, Svyatoslavite, Dmisteinbergite, Buddingtonite, Reedmergnerite, Slawsonite, Banalsite, Stronalsite and Lisetite.
The magical uses of Feldspars vary widely (for example, Labradorite, Amazonite, Moonstone and Sunstone all have very different metaphysical qualities) but the mineral group does have some properties believed to be common to all members. Feldspar is usually considered to be a lunar stone that encourages the development of clairvoyance and clairaudience (the ability to see and hear spirits). Any piece of Feldspar is useful if you are consciously developing your psychic or intuitive powers and it seems to be most effective if you work with the stone regularly while following a course of psychic exercises or meditation lessons. A charm bag containing three small pieces of Feldspar and a silver Moon pendant or charm is an excellent magical tool for these purposes.
Perhaps because Feldspar is found in so many places and so many varieties it has become associated with adaptability and the ability to cope with change. It is a good stone to keep near if you are feeling stressed by the pace of life or are dealing with loss, grief or changes that are affecting you emotionally or making you feel that your foundations are no longer stable. Feldspar can help you cope with the minor, everyday pressures of life as well as the major traumas. Taking some time out to meditate or just gaze at the surface of a piece of Feldspar, especially an iridescent variety like Moonstone, Labradorite or Amazonite, can really help calm and clear the mind. If done regularly the relaxing effect of 'stone-gazing' can provide similar benefits to meditation, including improving your concentration, lowering blood pressure and strengthening the body's natural defences against stress.