Wednesday, February 26, 2014

How to identify rocks and gems on a day hike with children

Among the great pleasures of day hiking is finding interesting rocks and even gems. Oftentimes, you’ll want to know the name of a particularly intriguing rock that you spot.

You can bring field guides on the hike, but spending a long time looking through them to find a rock can be frustrating and for any children with you will be quite boring. To quickly identify rocks in a field guide, you’ll want to note several characteristics of the stone in question.

As examining a rock you find on a trail, note these traits:
g Luster – Hold the rock into the light. Is it dull, waxy, glassy, etc.? Some minerals are translucent while others are opaque.
g Specific gravity – This refers to how heavy it feels or its heft. Different rocks of equal size will have different weights because some are denser than others.
g Crystal form – Is the rock thin, a cube, spherical, or another shape?
g Cleavage – How does the rock break? Does it leave smooth, flat surfaces, break irregularly, or something in-between? If the rock breaks irregularly, examine its fracture and see if it is jagged or splintery.
g Tenacity – How tough is the mineral? Does it crumble easily? Is it elastic? Is it extremely resistant to being broken?
g Hardness – How easily can a mineral be scratched? Will a fingernail do? A copper penny? Is a steel file needed?

Noting the color of a rock sometimes can be useful, but typically minerals are classified using the above categories rather than if it is gray, yellow, blue or something else.

Read more about day hiking with children in my Hikes with Tykes guidebooks.