Quartz is an abundant and versatile mineral. It can have microscopic crystals or quite large ones. According to its Wikipedia entry, "Its crystal structure is a continuous framework of SiO4 silicon–oxygen tetrahedra, with each oxygen being shared between two tetrahedra, giving an overall chemical formula of SiO2." Think of it as a silicon atom surrounded by four oxygen atoms where each oxygen atom is connected to another silicon atom. This structure page explains and illustrates the crystal structure in more detail. That site is a great resource for learning more about quartz.
Sometimes the way the crystals form and grow results in gemlike crystals such as agate, onyx, jasper, or amethyst. Other times, the result is the most common type of quartz - milky quartz. This quartz is white because other gasses or liquids were trapped in its crystal structure during its crystal formation. It may be translucent or even opaque rather than clear. Look here for pictures of milky quartz specimens.
On the Mohs hardness scale, quartz has hardness rating of 7 where diamond has 10, iron and nickel have 4, and talc has 1.
The cache container can be found next to the tree behind a rather large milky quartz specimen at
N 40 0.abc W 76 17.bbc where the values for a, b, and c are found by answering the questions below.
a = the number of oxygen atoms surrounding each silicon atom in quartz’s crystal structure
b= the difference in the number of letters in the two words of the English name of the most common kind of quartz
c= the Mohs hardness of quartz
Checksum of all digits in coordinates is 46.
If you are ever in Colorado and would like to hike a bit of the Colorado Trail, consider searching for Quartz Quarry Cache (GCKHK3).
Congratulations to ratjam on the FTF.