“The insolent quietness of stones”
While I wouldn’t consider myself a “rockhound” (one who is devoted to the collection of stones/rocks), I do love beachcombing for specific types of stones because of their color or texture or solidity or simply, because of their “insolent quietness.”
I love collecting Beach Stones. Or Beach Rocks. Or both! Wait! Is there even a difference or is it all semantics? Well, the common consensus among geologists is that there are some differences between the terms. ‘Stones’ (and pebbles) are restricted to smaller material. And stones are often fashioned into tools by humans. Hence, stone implies some sort of human use or small size. A ‘stone’s throw’, for instance, connotes something nearby. “Beach stones” are generally rocks one can pocket while beachcombing.
Although the term ‘rock’ can also be used in these situations, rocks can also be considered much, much bigger than stones. For instance, if a boulder falls down a mountainside, no one says, “Wow! That’s a big stone!” Or if a stone falls down a hillside and lands on your car windshield — then the rock does the same thing, which do you assume would do more damage? I’m banking on the rock.
So, in essence, geologists tend to regard all stones (and pebbles) as rocks but not all rocks as stones or pebbles. Got that?
Rock or stone, who cares? Let’s learn more about these wonderful beach treasures to aid you in your beachcomb I.D. forays.
The Earth’s crust is made of materials called rocks, some of which were formed 3.8 billion years ago. Rocks are made up of natural chemical substances called minerals. Some rocks contain only one mineral, such as marble, but most rocks contain crystals of several different minerals. Some of these minerals contain metals such as gold, iron and aluminum. Others hold prized gemstones (diamonds, rubies), or fossil fuels that produce energy (coal) or granite and sandstone people use to build structures.
There are three main types of rocks, and each one is produced in different ways. Sedimentary rocks (chalk, limestone, clay, shale, sandstone) cover 75% of the earth’s surface and involve the process of deposition, where fine rock particles have been worn away, grain by grain, layer by layer until they are eventually carried and deposited into oceans and lakes via by the wind, rivers or glaciers. Once there, the tiny fragments are compressed (squashed) and cemented together, which forms sedimentary rock.
Metamorphic rocks (like marble, slate) form when great pressure and/or heat – through volcanic eruptions or shifting tectonic plates – greatly altering the minerals already existing in primary underground rocks, so that these rocks transform into another kind of rock.
Igneous rocks (granite, basalt) are created when magma (molten rock) rises from deep underground, cools and solidifies at or near the Earth’s surface. Erosive forces sculpt their current forms.
Minerals are the building blocks of rocks. There are more than 3000 known minerals (the number is still growing), but of these only about 20 minerals are very common, and of these, only 9 constitute 95% of the earth’s crust. These 9 minerals are all silicates, and can be subdivided into the following groups:
Mafic Minerals: The term mafic is used for silicate minerals, magmas, and rocks that are relatively high in the heavier elements such as iron and magnesium. Some of these minerals include mica, feldspar, and olivine (which can be found on the Big Island).
Mafic rocks, like basalt, are overall of dark color though some are dark greenish ranging up to light and transparent. Older basalt rocks are especially abundant on the Maine and Washington coastlines. Newer basalt is abundant on volcanic islands such as those found in the Hawaii’s chain.
Felsic is a term used for silicate minerals, magmas and rocks which have a lower percentage of the heavier elements, and are correspondingly enriched in the lighter elements, such as silica and oxygen, aluminum and potassium. Felsic minerals include mica, feldspar and quartz. All of these minerals form through crystallization from silicate melts in the crust and mantle. Because Felsic minerals are light in color, felsic rocks are also typically of light color.
I love the way some beach stones feel. Soothing. Solid. Impenetrable. And I value my favorite beach stones (or rocks) as much as I do my other special beach treasures.
In fact, I carry one beach stone with me everywhere. It is a large orb of flat smooth quartz. And when it sits in the palm of my hand and my fingers smooth over it, it calms me down and/or comforts me. I am particularly drawn to both rose quartz and basalt brimstone, Oregon ocean agates and fossil corals that have turned to stone such as those found along Calvert Cliffs, MD. and Petoskey, MI.
Petrified wood, Washington State’s gemstone, is another beautiful rock and I went gaga pouring over the stony beaches of the San Juan islands where the rock colors stream down the color wheel spectrum from cream to yellow, to every shade of green, purple and red. I had never seen anything like it. More info…
For beachcombers who favor sea glass, don’t brush beach stones off too quickly. Know this: sea glass is largely composed of silica, much like quartz. Over millions of years, quartz breaks down into smaller rocks and then stones, some of which (the crystalline) are transparent and resemble sea glass (these specimens are often referred to as “Cape May Diamonds” because so many are found on beaches there).
As time and weather further break down quartz stones, they transform into small grains of sand. Beaches worldwide are composed of quartz sand. And if you heat quartz sand to 4200 degrees, it melts and transforms into glass (called ‘fulgurite’).
The circle of life. Or rock. Or stone. Or glass. Some of which rest in our pockets, to take home and treasure. To learn more, here is a good reference site for rock hounds: