No, its in the rarity. Gold only exists .004 ppm in the world. It has value because anyone that has looked for gold knows how hard you have to work to get it. If you know how hard someone has to work for something, you can put a value on it. For instance...if you know how hard it is to swing a pick and mine for gold and how much gold you find at the end of the day, then you know how hard it is for example to cut down trees all day as that is also laborous work. So if you know how much gold you get by mining yourself, you now know how much to pay someone to cut down trees for you all day. Obviously economics is not as simple as that and supply of labor, or demand for labor can increase or decrease pay for those types of jobs, but you get my point, I hope.
old nike woven nylon shoe laces are rare. desire or demand for things which don't keep you alive is all in the head.... just ask maslow. http://en.wikipedia.org/wiki/Maslow's_hierarchy_of_needs I would place gold in the Esteem level. If there were a limited supply of food or water.. gold would start going down in value rather quickly.
Man can not live on bread alone. (Luke 4:4) Eventually you are going to "want" something in your life and if everyone has bread and everyone has water, how do you get anything else in life that you want? You have to work for someone and produce something of value and instead of doing the barter method (I dont want 5,000 coconuts for my donkey) you find a better medium of exchange. Gold is a good measure of what a mans labor is worth. You labor for 40 hours looking for gold and at the end of the week you might have 1/4 oz of gold (more or less depending where you mine) Now i need someone to do labor for me and i know to pay them 1/4 oz of gold per week for their labor. My laborers also do not want to be paid in something as big as donkeys and coconuts. They want something that is small, easy to carry around and easily hidden to be kept safe. Gold works nicely for that.