[katieHaylor (OP)]

John says:

Sagan explained that we are all made from "star stuff" when humongous stars implode and/or explode to form the heavier elements. Why, then, do most compounds (e.g., gold, silver, iron, copper) appear in clumps (i.e., "lodes" or "deposits") instead of being mixed up with all the other elements?

What do you think?

[Kryptid]

Technically, many heavy elements are found mixed with lighter elements in the form of compounds (such as iron oxide, lead sulfide and mercury sulfide). Gold is chemically unreactive and thus tends to occur in a pure form.

[evan_au]

Why do most compounds (e.g., gold, silver, iron, copper) appear in clumps (i.e., "lodes" or "deposits") instead of being mixed up with all the other elements?

The Earth has experienced radioactive heating and geological "differentiation": Denser materials like iron and nickel are in the center, the least dense materials like nitrogen and oxygen gas on the outside, and intermediate materials like silicates (rock) and water (oceans) in between.
- Separation can also occur due to solubility: Certain elements are more soluble in the iron core, and other elements are more soluble in silicates or water.
- Further separation occurs because of temperature - as molten rock slowly cools, substances that solidify at a certain temperatures tend to be found together, forming an ore body.
- The same process has been at work in dwarf planets, and larger moons.
See: https://en.wikipedia.org/wiki/Planetary_differentiation

To find material which is in a more pristine condition, you must look to small comets, which have all these things mixed together, to a much greater extent. Because of their low boiling points, helium will be absent, and hydrogen will only be present if it forms chemical compounds with oxygen (making water), nitrogen (ammonia), carbon (methane), etc.
See: https://en.wikipedia.org/wiki/Halley%27s_Comet#Structure_and_composition

To find really pristine material, you must look to molecular dust clouds, which are the birthplace of new stars and planets. These dust clouds contain hydrogen and helium, and have a typical particle size similar to cigarette smoke, so there is little chemical concentration. But even then, they can form complex chemicals.
https://en.wikipedia.org/wiki/List_of_interstellar_and_circumstellar_molecules