Rocks or
Minerals What’s the Difference How to Guide
As a rockhound you love rocks and minerals, but we refer
to our collections as “rocks”. Sometimes we say “hey let’s go kicks some rocks”
or “Lets fill up a bucket of rocks” yet everything is not just rocks. I know
even I am guilty as our branding is “Radical Rocks”. Truly many of our most prized
“Rocks” are truly minerals. Now if you’re not a rockhound and you just stumbled
across this article, hang on because we will attempt to set the matter straight
in terms that the layperson should be able to understand. Rocks and minerals
make up our world and everything we use either came from them or was planted in
them or ate the plants planted in them. If you’re not a rockhound, by
default you still are a rock and mineral collector of sorts, because just about
everything you need and use day to day relies on rocks and minerals, from the
car you drive to the gas you put in it, to the food you eat, that is farmed
with equipment, fertilizer and pesticides, even organic farmers use rocks and
minerals, your appliances the equipment that makes your clothing, buildings
streets plains, everything we need to live either directly or indirectly
requires rocks and minerals. Rocks and minerals literally lay the groundwork
for all of nature from the sea, to the mountains and deserts, rocks and
minerals allow for a wide variety of environments and animals to live and reproduce.
Learning about rocks and minerals can create or improve on the following; math,
chemistry, science, geology, crystal formation and more. The beauty of rocks
and minerals itself if a good enough reason to learn what’s the difference
between rocks and minerals.
What are Rocks
Three different type of rocks are classified as; Igneous,
metamorphic, and sedimentary.
Let’s look at each.
1.Igneous; Igneous rocks come from lava
and Magma, and include rocks such as granite, obsidian, basalt and pumice.
2.Sedimentary; Sedimentary
rocks are formed from deposits of pre-existing rocks or minerals, even the
skeletal remains of once living microorganisms. These materials settle and
build up and become compressed and compacted and consolidate. The types of
sedimentary rocks include sandstone, shale, limestone, coquina, and castil.
3.Metamorphic; Metamorphic
rocks are formed when high temperature and high-pressure act on a rock and
alter its physical and chemical properties. Metamorphic rocks include phullite,
soapstone, gneiss, quartzite, marble, and schist.
What are Minerals
A mineral is a solid that can be made of a single element or a
compound. It is formed naturally by geological processes and must have the
following 5 characteristics.
1.Naturally occurring; No man-made
substances
2.Definite chemical composition; This definite chemical
composition is the same everywhere the mineral occurs.
3.Inorganic; not
living or from plants or animals.
4.Solid; at room temperature apart from mercury.
5.Ordered internal structure; which usually
forms crystals.
Lots and lots of minerals; at this time, we
have identified and named about 5400 minerals, about 200 of them are common and
of those 20 are very common. Here are a few that are very common Quarts,
feldspar’s, mica, talc, olivine, calcite, amphiboles.
Rock or Mineral clues
Rocks are; Made up of one or more minerals or
broken pieces of rock.
Minerals are; Made up of elements and
compounds.
Rocks may; Include organic remains.
Minerals contain; No organic material.
Rocks; Forms the solid crust of the Earth
Minerals; Makes up Earths rocks and sands and
is an important component of soils.
Rocks
and Minerals Physical test
Since this was
written to be a basic guide on the difference between rocks and minerals and
not a in-depth study we have included some basic information on physical
testing that will help you in the field to identify some rocks and minerals, we
suggest you dig in to this study further. (pun intended) A good field guide
will be used with the test that are described below.
Hardness;
minerals and rocks vary in their hardness, as represented by the “Mohs hardness
scale” 1 is the softest and 10 it the hardest.
1.
Talc
2.
Gypsum
3.
Calcite
4.
Fluorite
5.
Apatite
6.
Feldspar Orthoclase
7.
Quartz
8.
Topaz
9.
Corundum
10.
Diamond
Points of reference for comparison are as follows.
2.5 Hardness is your fingernail
3 Hardness is a copper US penny 1981 or earlier, newer pennies are
mixed with zinc
5.5 Hardness is a pocketknife blade of hardened steel
7 Hardness is a sharp pointed piece of quartz
You can narrow the hardness of the rocks or minerals as seen from
testing with the above items. For example, if you have found something that you
think is agate, usually agate is around 6.5 to 7 on the hardness scale. You
will scratch test it with your pocketknife, if it scratches a groove into the
rock or mineral it’s not agate. However, if you see a silver to gray line this
means the rock or mineral is harder than your pocketknife, and the knife has worn
a bit of itself on to the rock and could possibly be agate.
Streak test
The streak test is done by rubbing your material on a piece of unglazed
Porcelain, the back of an old glazed tile will work. You then look at the
color, this can help Identify a rock or mineral in your field guide.
Color
The actual color or colors may also help in identifying your rock or
mineral.
Cleavage
Not that kind of cleavage, it has to do with the tendency a rock or
mineral must break or be formed in a certain direction or way. Think of
crystals for this visual test. If it looks like a cube, its cleavage is a cube,
and so on. Some examples are, orthorhombic, rhombic, cube, octahedral. Refer
again to a good field guide. I will add some field guide suggestions at the
bottom of the blog.
Luster
This is how the reflection of light is on the surface of your rocks or
minerals. Some examples are, silky, greasy, sparkling, metallic, glassy, or
pearly.
Fracture
This is how the rock or mineral breaks apart if you walk it with a
hammer. (always use eye and face protections, rockhounds don’t look as good
with a tooth missing or an eye injury) Some examples are, hacky, uneven, even, conchoidal.
Specific Gravity is one you will not likely want to do in the field. It
is simply weighing your sample on a balance, and getting the exact weight, then
weigh the same sample as its suspended in water, then take the weight in air
reading and divided it by the difference between the weight in the air and the
weight in the water. Your field guide should help with this.
Finally, there are chemical test that can be done as well as flame test
that can be done if you wish to take it to that level. I have included a link
to a to a website that has a flow guide/chart to identify common rocks or
minerals.
Now you will be able to correct your rockhounding partner if they don’t
know the difference between rocks and minerals, or you could send them here.
Join me on the
Radical Rocks Podcast, our Blog or social media below, also
see our affiliate links below that help support our mission to keep
Rockhounding and lapidary arts alive and thriving. Feel free to contact me
with any suggestions on this blog or any other ideas you may have. If you would
like to sponsor in some way, or have your club, book, or mine, spotlighted in
Radical Rocks, Blog, Podcast or Video’s feel free to contact Shane with Radical
Rocks.
Affiliate/referral
links
Field Guides to Identify Rocks and Minerals
Smithsonian handbooks; Rocks and Minerals https://amzn.to/2UKnH3x
National Audubon Society Field Guide to Rocks and Minerals: North America https://amzn.to/2OOzsC5
My Awesome Field Guide to Rocks and Minerals https://amzn.to/2uusECT
The Illustrated Guide to Rocks & Minerals: How to Find, Identify and Collect the worlds Most Fascinating Specimens https://amzn.to/38niJxE
Rock and Gem: The Definitive Guide to Rocks, Minerals Gemstones, and Fossils https://amzn.to/31MpJRU
Tools for Rockhounding
Good Rock Hammer https://amzn.to/3bxxD6o
Rockhounding Tool Kit https://amzn.to/2SPVq9d
Pocket Magnifying glass/ loop https://amzn.to/2Skpw5n
Field Guides to Identify Rocks and Minerals
Smithsonian handbooks; Rocks and Minerals https://amzn.to/2UKnH3x
National Audubon Society Field Guide to Rocks and Minerals: North America https://amzn.to/2OOzsC5
My Awesome Field Guide to Rocks and Minerals https://amzn.to/2uusECT
The Illustrated Guide to Rocks & Minerals: How to Find, Identify and Collect the worlds Most Fascinating Specimens https://amzn.to/38niJxE
Rock and Gem: The Definitive Guide to Rocks, Minerals Gemstones, and Fossils https://amzn.to/31MpJRU
Tools for Rockhounding
Good Rock Hammer https://amzn.to/3bxxD6o
Rockhounding Tool Kit https://amzn.to/2SPVq9d
Pocket Magnifying glass/ loop https://amzn.to/2Skpw5n
Fundrise, become a real estate investor for only $500 I have for months
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Guides for identifying rocks and minerals
Rock Identification: A Compendium of
Classifications (The Earth Science Series Book 2) [Print
Replica] Kindle Edition
by Bernhard R. Teicher (Author)
A great one even if you’re not from California as it walks you through
steps to identify your rocks and minerals, worth getting even if it’s out of
print, Rocks and minerals of California. By Vinson Brown and David Allan
Rock Identification by Patrich Nurre. I have not read this one.
Guide to
identify a common rock or minerals, just scroll down the page to the “Rock Key”
section. http://www.rockhounds.com/rockshop/rockkey/index.html
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