Steve Woods

The Joys and Needs of Rock Collecting

In What Day is it? on September 16, 2009 at 10:31 am
Pretty rock collection.

Pretty rock collection.

Since our beginnings, interesting rocks discovered in nature have been imbued with special, even spiritual qualities. Beautiful or uniquely shaped stones were often believed to have been placed by divine forces to be found by the lucky recipient for an unidentified purpose or as a prize.  Stones with appealing or desirable qualities such as brilliant crystals and gems were traded far and wide, used in rudimentary jewelry or even worship.  The ability to both correctly identify and manipulate flint was the difference between life and death in many battles. There is a better than average chance that you are here today because some primeval ancestor of yours had this skill, a sharp eye and good throwing arm.

As children, we are drawn to the rock. We picked them up when our parents weren’t looking, holding the incredible textures in rapture on our fingertips, perchance to loll them in our mouths until rebuked. We carried them around all day in little pants pockets, tucked into the side of sneakers, or in sweaty hands. We learned to toss them and enjoyed the fine snick they made when they hit the pavement. We soon discovered the ability to draw lines with softer rocks on the sidewalk or street, or involved ourselves in contests of skill, skipping them across oceanic puddles, reveling in our ability to launch a perfect-sized rock into near-orbit.

A few of us never gave up the idea of saving special rocks, collecting them and storing them away, sharing them with our children and explaining how they came to be.  We tie memories into the finest of our gemstones, mounting them on our fingers in commemoration of first communions, graduations, weddings, births.  To be sure, there remain rocks that seem to maintain their appearance of divine gifts, adding purpose to our lives simply by being a part of it. It is never too late in life to begin collecting anew, and reintroduce yourself to that special relationship you once had with the rock.  Just keep them out of your mouth, okay?

Types of rocks

It is important, when collecting rocks, to know what you are looking for. Here’s an extremely simple breakdown…

Igneous

As magma cools it undergoes a phase change into a crystalline form. The more rapid the cooling, the smaller the crystal size. Rocks that formed deep below the surface, with its heat insulated, are called intrusive, and typically have large crystals. Rocks from volcanic eruptions, exposed to the surface and cooled rapidly, are called extrusive, and have smaller crystals.

Igneous rock slideshow

Sedimentary

The igneous rocks forming the majority of Earth’s crust have a fine layer of sediment on them. Over time, more and more layers of sediment build on, hardening over time due to pressure. When pieces of the hardened sediment break off, they are called secondary, or sedimentary rocks. There are three types of sedimentary rocks: Clastic, formed by little pieces of sedimentary accumulations; Chemical, formed by evaporating water leaving chemicals behind; and Organic, caused by layers of organic processes (deposition of shells, bones, teeth, etc.)

Sedimentary rock slideshow

Metamorphic

Getting their name from “meta” (change) and “morph” (form,) all rocks are capable of becoming metamorphic. An igneous or sedimentary rock, moved from its place of origin and introduced to pressure and temperature changes, can change its form. Common examples are slate and marble.

Metamorphic rock slideshow

Rock Collecting Tools

Although simply picking up and keeping rocks is easiest, if you would like to make a lasting habit of it, and want it to take over your life, you’ll need some of the following:

  • A geologist’s hammer, either pick-axe shaped or chisel ended. This implement is used to break off fresh specimens and then trim them down to size (no, you are not stuck with a big rock if that’s what you come across…)

    geologist_hammer

    Geologist's hammer

  • A magnifying lens (6x – 10x work great) of high optical quality (can be found at many jewelers’ stores or optical stores) to observe the rock’s grain close up.
  • A strong knapsack to carry your rocks and equipment.
  • Individual bags and possibly packing materials to carefully separate the rocks if needed. Some specimens can be brittle…
  • A notebook for keeping field notes.
  • A camera for taking photos of the area you found the specimen.
  • A GPS-enabled device to help you re-locate finds and to help get you back safely.
  • A pocket knife.
  • Sledge hammers or cold chisels to break off specimens.
  • First Aid kit.
  • Protective clothing (jeans, sturdy shoes, gloves, eyewear)
  • Diluted hydrochloric acid to clean off stones and to help identify certain stones such as limestone and dolomite.
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