Unless you have 40 acres for display and a gold mine to support it, you'll need to decide what kind of collection you can enjoy and support.

It's easier to excel and stay active in your collecting if you focus on one field, such as; one group (like petrified wood), a crystal system, or one mineral (like quartz).

If quartz is your passion, you're in love with Silicon Dioxide.  Once in the oxide group, quartz is now considered in the Silica group. 

On the basis of appearance, there are 2 groups of quartz; crystallized and microcrystalline.  We can refine the 2 groups even further.  The microcrystalline group can be subdivided into parallel fibrous crystals and mixed granular.

• Crystallized quartz can be colored or colorless.  These are your amethyst, smoky, and massive milk and rose quartz.

Look for Amethyst                   

• Chalcedony is translucent and has slender fibers in parallel bands.  One example of obvious translucent banding is agate.

Look for Banded Agate         

• More impurities and more opaque is the chert (tans and browns), flint (blacks and grays - sparks when struck with a hammer or another rock), and jasper (reds, oranges, etc) groups of microcrystalline quartz.

Quartz is a geological thermometer with 573 degrees being the first magic number.  It can occur almost anywhere.  It has a hardness of 7, specific gravity of 2.6, fracture is conchoidal, and cleavage is rhombohedral. 

Silicon Dioxide is an important industrial material and a quartz outcropping is a prospector's solid clue to the gold, silver, or copper motherlode.

A rock, mineral, or fossil collection is a rewarding and educational hobby.  It's very personal and no two collections will ever be alike.  Happy collecting.