Thanks. That was just a recollection from a book I read many, many years ago and no doubt faulty or perhaps it was based an the best information available at the time. I have a source (which I can't cite at the moment) which states that gold constitutes > 0.000001% of crustal matter. Most plentiful are:

oxygen @ 46.6%
silicon @ 27.7%
aluminium@ 8.1%
iron @ 5.0%
calcium @ 3.6%
sodium @ 2.8%
potassium @ 2.6%
magnesium @ 2.1%

If I remember right titanium falls in the next spot or so right around 2% but it is very abundant in the soil and its accessibility in effect places it about 5%. The light stuff tends to float up. The little list I gave accounts for 98.5% of all crustal matter. Of course the oxygen is chemically bonded to the aluminium and silicon and most other things it comes in contact with and yet there is still around 18% free oxygen in the atmosphere, thank God. It's kinda hard to breath without it!

Carbon is fairly rare in the overall scheme of things yet abundant on the surface, kind of like titanium. But it combines so nicely with hydrogen and oxygen and that little benzene ring is such a handy and universal tinker toy you can build just about anything out of it, including living creatures. And C sub 12, H sub 24, O sub 12 is so sweet, I can't live without that either (table sugar)!

Gold is so soft and malleable that the coinage wore out too fast to be a good circulator. Historically it was not circulated that much but rather hoarded and mostly by royalty. A commoner with gold was a suspicious character at best. Precious metals were usually in the form of dinnerware, a spoon or fork of silver or partially silver represented the family wealth (portable wealth as Dickens was oft to write). 24 carat gold is pure gold (.999 fine) and 12 carat is 50% gold. That gives you the scale. 10 carat is as low as it goes. Other names apply after that, gold fill being one. If you drag a cloth across gold fill it comes off a black mark. About 2 % gold. 14 to 18 is what you usually find in jewelry in the States. It has a good portion of copper and a little nickle in it to make it harder and last longer. For some reason Europeans like the 20 to 22 carat stuff. Why not! More gold. More portable wealth!