Bushcraft Relevant Rock Recognition. PART 1

auscraft

Henry Arthur Readford
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Bushcraft Relevant Rock Recognition. PART 1

Hi all
In response to Blake’s thread The Bushcraft Topic Pin boardand a suggestion of topics by Hairyman, I have decided to start with rock recognition.

Let me start by stating I am a not an expert on this subject and will not be surprised if members here have far more knowledge than me. Infact till very recently the facts I knew about rocks could be counted on thefingers of one hand. I am out of my field here, but this is a starting place for my own learning and hopefully others.

What I knew before recent times and this one does not countas I often if not always argue is I have been told “I have rocks in my head” (as I write this I am thinking they may be right).

Prior facts;
1. Rocks were used by primitive man as tools formany things e.g. tools, weapons and fire starting.
2. People who live in glass houses should not throw rocks.
3. A guy name David slain a guy named Goliath.
4. Somerocks cost a lot of money.
5. River rocks should never be placed in or nearfires.

As this Tutorial is directly related to rock recognition in regards to bushcraft I will concentrate on the rocks mentioned in the following thread http://bushcraftoz.com/forums/showthread.php?3344-Stone-tool-resources. And will be continually added too.
A couple of questions I hope to answer here today are

1. What did we or primitive man want the rocks to be used for?
Basically we want to learn the skills of our primitive ancestors in a nut shell. For them it was a resource that offered them Fire,Tools and Weapons. Yes by striking certain rocks together it gave them a means to light fire. By shaping the stone gave them tools and weapons for defence, hunting food processing and much more.

2. How did Primitive man recognise rocks for certain tasks?
Trial and error, then the info was passed on and shared and if they moved the process started over again.

3. How do we recognise certain rocks?
One way is to do as our ancestors did it trial and error. But wait on we live in the 21[SUP]st[/SUP] century isn’t there an easier way? YES and NO. We have the benefits of years of research and information being passed and new information sharing technologies like the WWW. But unless you buy the rock or have studied geology you still need to be able to identify them and find them.

Let us Start
I recently been attended rock club meets and shows and to tell you the truth very few of these people who were interested in lapidary were able to answer do you have any chert or can you tell me what I need to look for, But when I meet the few that truly knew anything they could not be anymore helpful sharing the info I asked. I thank them greatly; it is just more proof old knowledge is dying out.

Categories

Rocks generally fall into one of three categories they are igneous rocks, sedimentary rocks and metamorphic rocks then there is a fourth which are not genetically distinct. Without going into more depth than needed here I will use a link on the rock types in these categories.http://en.wikipedia.org/wiki/List_of_rock_types

Physical properties.

The properties that most of us want to know about for Bushcraft are rock types used for Knapping and fire lighting. In both case we require rocks with a hardness of 7 or more on the Mohs scale. Basically the Mohs scale is a score from 1 – 10, 10 being the hardest and means scratch hardness.

The way to test rocks for hardness is not all that hard and requires a few tools to test and I would say as Bush crafters you most likely carry most of them anyways. They include;
· Fingernail
· Brass coin
· Iron nail
· Glass
· Penknife
· Steel rasp
· Sandpaper
· Knife sharpener

To explain a little more a list of 10 test stones showing how the scratch test works. http://en.wikipedia.org/wiki/Mohs_scale_of_mineral_hardness
My list with the tools listed above showing same results
1 Talc= soft, 2 Gypsum =finger nail, 3 Calcite =coin, 4 Fluorite =iron nail, 5 Apatite= glass, 6 Orthoclase= penknife, 7 Quartz= rasp, 8 Topaz =Sandpaper, 9 Corundum=sharpener, 10 Diamond= nothing.

Without going into any other details not truly relevant tous as Bush crafters, I will now refer to the list again at http://bushcraftoz.com/forums/showthread.php?3344-Stone-tool-resources. So from the list given and the knowledge of the Mohs testing is there anymore info that can help us recognise or help us find the rocks required for ourneeds? YES

http://en.wikipedia.org/wiki/List_of_rock_types will help us with a description of the rocks we are looking for. However youwill find knowing a name for the rock you are looking for the most helpful. It will with research show if the rock is available to your area and the generally and features to look for them. For example Chert is a general name for a rocktype meeting certain structures but if you search for Gympieite you discover this as being is a type of blue and green chert formed from ancient silicious (foraminiforous) sediments in deep water. These deposits found near Gympie Q. Or search Prostonite , This is an interesting type of chert that occurs in only one location in South East Qld. Further researches can be even more helpful but don’t do general searches of a general name.
But we will still need to test to see if it is a appropiate or best to suit our needs not all cherts or rocks are the same.

As I have said my knowledge is limited and open for help in these matters if I have helped anyone I am very happy. Hopefully as time goes on and time being available I will include pics and names of rocks to look for. Anyone who can help with any info please contribute.
If you have any questions please ask I won’t take offence I too am learning and may easily over looked some info passed onto me already. My own knowledge is growing and had some very nice offerings to help me learn including field trips and question answering from a very knowledgeable person in this field.
 
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auscraft

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I had trouble uploading the info above so had to delete the pics will add some here soon I promise
I am also correcting the formating from upload on the above post
 
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Aussie123

Never Alone In The Bush
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Fantastic work auscraft. Let me add a bit too :


To learn about rocks you generally need to have an understanding of minerals. That is because all rocks are comprised of one or more mineral.

If rocks are comprised of one or more minerals, what’s a mineral ?

A mineral is can generally be represented by a single chemical formula eg quarts is SiO2 (Silicon dioxide) and has a crystalline structure (like a hexagonal quartz crystal).
q.jpg

A mineral has a set of properties like hardness, crystal shape, cleavage, colour and streak, specific gravity, refractive index etc

Aggregates of (one or more) minerals form rocks.

How those aggregates come about could be via natural processes like super heated material coming from deep below the earth’s surface; the action of water (oceans, lakes, rivers, tsunamis); heat from the Earth’s core or other forces; immense physical pressure; or a combination of these.

- - -
Mohs scale (of hardness) generally refers to the hardness of minerals, rather than the hardness of rocks, since a single rock can be comprised of many minerals, some of which may be hard and some soft.

A classic example of a rock is granite. (I generalize greatly here, people literally have PhDs on the subject ). Granite is generally comprised of 3 (or more) principal minerals :

Quartz: appearance: clear and colourless, sometimes milky, hardness: 7;
Feldspar: appearance: white, creamy or pink, hardness: 6; and
biotite: appearance: black, hardness range: 2.5 – 3

Have a look at some city buildings, monuments in town, even some kitchen tops; granite is a common building material

Typical looking granites (pics from the internet). See the details of the different minerals ?
g1.jpg g2.jpg g3.jpg

So a rock like granite does not have actually have a “hardness”, but its constituent minerals do.


Other rocks consist of a single mineral eg sandstone.
Sandstone is comprised of many grains of sand (like on a beach), all fused into a single mass. Sandstone is comprised of (generally) quartz sand and quartz has a hardness of 7.

Depending on how well imbricated (fused) the quartz particles are will determine the grade of the sandstone, hence its suitability for building etc and I guess we (bushcrafters) would percieve that as its "hardness" (but actually the hardness of all quartz sandstones is 7)

In your travels perhaps you have noticed some very soft and crumbly sandstone where individual sand grains may rub off or be visible, and elsewhere it may appear like a solid mass with no individual pieces visible ?
 

auscraft

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koalaboi

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Hi,

Great thread.

I am nit picking I know, but should we refer to our ancestors and their knowledges as primitive?

The thing to look for in knappable rock is concoidal fracture. See here:

http://bushcraftoz.com/forums/showthread.php?261-Chert-knapping/page4

For ground edge stone tools, fine grained, homogenous hard rock is the go. Basalt is good but other rocks are fine. Getting geologists to settle on a name for a piece of rock is not easy either.

Kb
 

Bartnmax

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'Auscraft wrote;
"Prior facts;
1. Rocks were used by primitive man as tools formany things e.g. tools, weapons and fire starting.
2. People who live in glass houses should not throw rocks.
3. A guy name David slain a guy named Goliath.
4. Somerocks cost a lot of money.
5. River rocks should never be placed in or nearfires."

I'd also add;
6. "when carrying one's rocks around in public it is generally frowned upon if they should happen to fall out of one's carrying container.
This is often refered to as 'getting one's rocks off' & is definitely not socailly acceptable in said public domain".

Bill.
Shoulda been a geelolagist mesef.
 
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