Rock Hounding
Rock Hounding
A rock hound is defined as an amateur mineralogist, but really it’s someone who enjoys collecting interesting rocks and minerals. The term rock hound includes people who casually pick up something that catch’s their eye and serious collectors who enjoy rock and mineral samples at rock and gem shows around the country.
Anyone can be a rock hound. If you have ever pickup up an interesting looking rock on a walk or at the beach, then you have already started the process.
It’s neat to build a collection of minerals and learn what they are and what they can tell us about the natural history of of our area and the creatures that lived here. A perfectly formed crystal is a beautiful thing, and there is always the possibility that you will make an important discovery that may end up on display in your local museum, mostly though you will be able to accumulate a collection that will draw the interest of all your friends and family.
Just for the Fun of it
Everyone can enjoy rock hounding. Rocks are everywhere and you don’t need much in the way of equipment to get started. Therefore, any family outing can easily be turned into a rock hounding expedition and if you want to the search can be the focus of a major wilderness hiking trip.
One you start learning about rocks and minerals, you will be amazed at how interested other people are in what you have learned. Everyone has an interest in the earth and a rock hound has the advantage of being able to satisfy some of that natural curiosity. Rock hounding can also lead into lapidary (cutting and polishing rocks) and jewellery making or perhaps into the scientific fields of geology, such as paleontology, mineralogy and petrology.
Organizing, cataloguing and labelling the specimens you have collected and identified on your own can be very satisfying. Your collection will be unique and will continue to grow and change as you go on collecting expeditions or as you trade samples with friends and other collectors.
What to Take with You
Of course it depends on how seriously you pursue the activity. Obviously, if you are planning a three day hiking trip to a remote site, you will need all the gear necessary for such an undertaking. However, for an afternoon’s collecting close to home you can get by with the basics.
Basic Items necessary for Rock Hounding
Hammer: Geologist’s pick or a mason’s hammer (not a regular hammer as this might chip when used on rocks)
Chisels: 1 to 2.5 centimetre size
Day Pack: To carry your tools, specimens, lunch and emergency kit
Plastic Bags: To hold your samples.
Newspaper: To wrap your samples, fragile samples can be wrapped in toilet paper or paper towels and small samples can be stored in egg cartons.
Safety Glasses: Goggle-type is best, bus some plastic sunglasses can double as safety glasses.
Recording Devise: Notebook, pencils and marking pen.
Clothing: Appropriate clothing, rain gear, sturdy boots or shoes and a change for when you are done.
Also Consider:
Hand Lens: Can be carried on a string around the neck and is invaluable for looking at details
Gloves: Some rocks can have sharp edges
Hardhat: If you are going in or near quarries, steep banks or cliffs.
Some Extras: Sledgehammer, wedges, screwdriver, gardening tools, pry bar, rake and screen, pointed shovel.
Extra Maps: Detailed maps of geology, topography, etc.
Altimeter: If you are off road a GPS and an altimeter will fix your position on a topographical map.
Survival Kit: The same you would carry for a hike, also a first aid kit.
Books: Geological guidebooks and geological maps, mineral and rock identification books.
Where to Look
Geologically, Vancouver Island is very diverse. This is because it’s actually made up of a lot of micro-continents that have become welded into one island. This also partially explains the ruggedness of the island. Because of the diversity of rock, the potential for mineral occurrences is immense, a virtual frontier for rock hounds with countless exciting sites waiting to be discovered.
Anywhere rocks are exposed is potential for mineral and rock collecting. Rocks commonly outcrop along steep hillsides, in gullies, river and stream beds, road cuts, building excavations and quarries. Even where there is no sold rock, minerals may be picked up from debris slopes, gravel deposits, old mind dumps, beaches and a dried lake beds.
If you are collecting on private land make sure you have the owner’s permission. If you’re going on a public land check to see if you need a permit, disturb things as little as possible. Close the gates behind you do not interfere with livestock and fill in any large excavations you make and most of all DO NOT TRESPASS.
The easiest specimens to find are the ones that have already weathered out of the rock. Always look around on the ground to see what’s there; it can sometimes save you a lot of hammering.
Many good samples will not be as easy to obtain and you will to dig them out of the rock. Never try to pry your sample directly out of the rock, it is much better to take some of the surrounding rock as well. This will protect the mineral and allow you more flexibility in designing your displays.
Try to use the natural planes of weakness in the rock to your benefit. Look for cracks and drive in a wedge or chisel. Work around the sample, but not too close or it might fracture. Take more rather than less, you can always remove the excess later. Be patient, the mineral has probably been in the rock for millions of years; it might take a while for you to get it out.
What did you Find?
Different minerals have different properties and these can be used to identify them. Often you will collect a mineral without knowing what it is, identification will have to wait until you get home and can study it at leisure. But, the more minerals you collect, the better you will become at identifying them. Some of the properties used to identify minerals are colour, streak, form, cleavage, lustre, density, hardness, magnetic response and reaction with acid. There are many books in the local library which will provide you with the information you’ll need to understand and use these properties.
It’s easy to put together a small rock and mineral identification kit that will fit in your pack or pocket.
You will need:
A Hand Lens: 10 or 15 power with a wide field of view.
Penknife As well as being useful for digging into soft rocks, this is useful for determining hardness.
Streak Plate: Minerals often leave a streak when scratched on a small, white, non-glossy ceramic tile. This streak can be different from the mineral’s colour and is useful in identification, (5%) Dilute (HCI) muriatic Acid. This should be carried in a small, leak proof, plastic dropper; otherwise it will rot your clothes!
Guide Book: A good mineral identification book, listing the properties of the minerals you are likely to find.
Magnet: A larger variety is better but any magnet will do.
Where did you Find it?
Even the most extraordinary mineral treasures cannot remind you where you found it. The first step when you find a specimen is to label and record where it came from. Create a number for it; this should be systematic, perhaps using your initials, the date and a locality code. Mark the number on the sample, sometimes this can be done with making tape and a marker or a piece of paper can be put in the sample bag. In either case the bag itself should also be labelled.
Then you record the same sample number plus the identification (if you know at the time) and the date, location and a description of the rock in which you found the mineral in your notebook.
When you get home you should clean your specimens. Excess rock can be carefully chipped off. Old dental tools are good for detailed work. Dirt can be washed off with soapy water and a soft toothbrush and a permanent label should be attached. A good way to label your mineral is to paint a small white strip in an inconspicuous place and write your sample number on the white paint.
The permanent sample number should be written on a card or in a catalogue along with the information from your field book and whatever else you have been able to find out about the specimen. The specimen can then be stored in a drawer or displayed for all to see.
How is the Rock Formed?
Finding the rock is only the first step in rock hounding. It helps to know what kinds of minerals you are likely to find in differently types of rock.
Minerals need space to grow. The chemical, physical and temperature conditions might be just right, but if there is no room for a crystal to grow it won’t form, cavities are found in all rock types, sometimes they are related to the rock itself or they may be the result of something which happened after the rock formed like cracks and fissures due to faulting and folding.
Veins and dikes are prime hunting-ground for mineral specimens. Both form a sheet-like body cutting the other rocks and commonly contain larger than normal crystals, or may be composed of a single valuable mineral. The forces which create veins and dikes may result in cavities which can later fill with good mineral crystals.
Do you know which Rocks to look at?
All rock types have the potential to contain interesting mineral specimens, however, different rocks contain different minerals and knowing which is which allows you to use geological maps and to zero in on areas that are likely to be interesting.
Igneous rocks are formed by the crystallization of molten material (magma) from deep within the earth. If the magma reaches the surface it cools quickly, forms small crystals and is termed extrusive (e.g. basalt lava) If the magma does not reach the surface it cools slowly, forms large crystals and is termed intrusive (e.g. granite).
Pegmatite is a good example of an intrusive igneous rock. It commonly occurs as dikes associated with granitic rocks and generally consists of large crystals of quartz, feldspar and biotitic, however, some pegmatities also contain large crystals of tourmaline, beryl, garnet, spodumene, fluorite and muscovite.
Basalt is an extrusive igneous rock. It commonly contains cavities resulting from gas bubbles which were trapped as rock cooled. These cavities (amygdules) may contain agate, quartz, amethyst, chalcedony, calcite and zeoltes. When the mineralized cavities weather out they are called geodes or thunder eggs. Basalts may be easily found around Northern Vancouver Island, Quadra and Texada Island.
Sedimentary rocks are formed by the compaction of sediments such as sand, gravel or clay, or by chemical precipitation to form rocks such as chert or travertine.
Chert and Jasper are found on Vancouver Island as well as travertine.
Metamorphic rocks are formed by the alteration of already existing rocks, whether igneous or sedimentary. High pressures and/or temperatures usually bring about the changes in mineralogy. The minerals present in metamorphic rocks depend upon the original rock type.
Metamorphosed ultramafic rocks may alter to serpentinite which can be associated with jade, soapstone, rhodonite, idocrase an chalcedony but are not common on Vancouver Island.
Marble; a common rock on Vancouver Island is metamorphosed of limestone and may contain garnet, scapolite, tourmaline, epidote and wollastonite. Schists and gneisses may also contain garnet, staurolite, sillimanite, andalusite, kyanite, rutile, corundum and spinel.
By no means is this a complete list of possible rocks to be found on the island. For more information:
Resources
Meet 2nd Friday every month at the Croft Room at the Campbell River Community Centre, 401 – 11th Avenue, Campbell River. The Club has an annual show with dealers, demonstrators and activities for children.
The Bugle, is the Club’s newsletter which members receive each month (except July & August). It keeps members informed about upcoming meetings, field trips, camps, activities, resources, member profiles, information for Juniors, show, and events throughout the province organized by the BC Lapidary Society and which members are welcome to attend.
Beware
Old mine sites, quarries and gravel pits are potentially dangerous places. There can be shafts and holes hidden by vegetation, cliffs and mined slopes that are unstable and likely to collapse, complex underground tunnels may be filled with poisonous gases. Always be aware of the possible dangers around you.
Never enter those old workings to collect minerals and always let someone know where and when you’re going on rock hounding expeditions. You should always collect with a friend!
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Are there any loose rocks which your hammering might bring down?
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Watch for rock falls and never walk directly above or below another person on a slope.
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Does the head look like it is about to fly off and injure you or your buddy?
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Always hammer away from yourself.
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Are you wearing your safety glasses?
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If you are going in to the backcountry, learn how not to get lost, learn what to do if you do get lost and learn basic wilderness survival.
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Follow obvious geographical features (ridges, creeks, rivers) which take you in the right direction.
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Keep a mental note of the landmarks you pass (a fallen tree, the number of creeks crossed).
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Bring your GPS; don’t leave it in the car.
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Avoid getting wet whenever possible.
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If possible talk to someone who has recently been where you plan to go.
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Let someone know where you are going and check in with them when you get back.
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Know how to react to any wild animals you may meet.
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Carry emergency gear, dress appropriately for the weather, check the weather before you go out and allow enough time for all the things you want to do.
Some Helpful Geological Terms
Agate
A translucent, extremely fine-grained variety of quartz which is characterized by colours arranged in alternating bands, in irregular clouds or in moss-like forms. Usually forms in vugs or cavities in volcanic rocks.
Amethyst
A pale purple to violet variety of crystalline quartz, the colour is due to iron compounds.
Amygdule
A gas cavity or vesicle in an igneous rock which is filled with secondary mineral such as quartz, calcite, chalcedony or zeolite, an agate pebble could be referred to as an aygdule.
Andalusite
A brown, yellow, green, red or grey mineral which occurs in thick, nearly square prisms in schists, gneisses and rocks altered by heat and pressure.
Arid Area
Areas, such as deserts, which have little or no rainfall.
Basalt
A general term for dark coloured bolcnic rocks composed chiefly of the minerals plagioclase and clinopyroxene.
Basalt Lava
Basaltic rocks which are formed as lavas on the earth’s surface.
Beryl
A green or bluish-green mineral which includes the varieties known as emerald, aquamarine, heliodor and golden beryl.
Biotite
A common and important rock-forming mineral which belongs to the mica group of minerals, it is generally black or dark brown and has a characteristic platy form and can be split very thin, transparent layers with a fingernail or sharp knife.
Calcite
A common rock-forming mineral, CaCO3, it is usually white or colourless and is very soft. Calcite usually fizzes in weak hydrochloric acid (muractic acid) and this is a test used by geologists to see if a mineral is calcite.
Cavities
Small, usually rounded opening found in volcanic or sedimentary rocks, frequently cavities may be filled with quartz or calcite to form geodes or nodules.
Chalcedony
A very fine grained, or cyptocrystalline, type of quartz which forms concretionary (rounded) masses. Chalcedony is contained in most chert.
Chemical Precipitation
A process by which molecules are deposited out of fluids to form rocks or minerals, agates and cherts are commonly thought of as chemical precipates.
Chert
A dark, extremely dense very fine grained, or cryptocrystalline, sedimentary rock consisting dominantly of quartz, usually the chalcedony variety.
Cleavage
The crystal planes of a mineral along which it tends to break.
Concretion
A hard compact mass or aggregate of mineral matter which is normally rounded by may be very odd shaped. They are usually formed by chemical precipitation.
Corundum
A very hard mineral composed of aluminum and oxygen, A1,O3, which is used as an industrial abrasive. Gem varieties include ruby and sapphire.
Chrystal
A solid body of a single chemical element or compound which has a regular shape and which has a surface defined by flat faces, quartz, emeralds and diamonds are naturally occurring minerals which form crystals.
Debris Slope
This is a material at the base of a high cliff or slope which is composed of fragments and boulders of the rocks and minerals which have been weathered from the cliff face above, may also be referred to as a talus slope.
Dried Lake Bed
Material composed of lake sediments which are left after lake waters have evaporated or drained off. Salt is a common mineral which forms in the beds or sediments of a lake which dries up.
Epidote
A yellowish-green mineral which commonly occurs in limestone which have been metamorphosed, or altered by heat.
Excavation
Trenches, adits, pits and other workings created by prospectors, miners or Rock hounds to dig out interesting minerals or rocks.
Extrusive
This is a molten rock which is forced out on to the under face of the earth to cool an intruse rock, on the other hand is one which cools from a magma stage to a hard rock somewhere below the earth’s surface.
Faulting
Flat or planar features along which the earth’s crust breaks and moves, earthquakes are normally caused by movement of one rock against another along a fault.
Folding
Although most people don’t realize it, rocks are quite plastic over hundreds of thousands of years. The normal movement of the earth’s crust results in much pressure which in many cases will fold rocks. Much the same thing happens if you take a blanket, lay it flat on the floor and then push one edge towards the other with your hands-the blanket folds in a short time; rocks do the same over thousands or millions of years.
Feldspar
Feldspars are the most common, rock-forming minerals and constitute 60 percent of the earth’s crust. They include gem varieties such as labradorite and they weather over time to produce clays.
Fissure
A surface or crack in the rocks along which there is a distinct separation. Fissures commonly result from movements caused by earthquakes. Old fissures are commonly filled with minerals such as quartz and calcite.
Fluorite
A transparent to translucent, relatively soft, mineral found in many different colours. It is commonly found in association with ores of lead, tin and zinc metals and it may occur in large enough masses to be carved of ornamental objects.
Garnet
Garnet is a name for a group of similar minerals, including varieties known as almandine, andradite. It is usually red or orange in colour and is commonly used as an abrasive. Large garnets, particularly dark red ones, may be cut as semi-precious stones; a variety called pyrope is a beautiful mauve to purple colour and is commonly associated with diamond deposits.
Gem
Any rough natural material that can be fashioned into a jewel.
Geode or Thunder Eggs
A hollow, or partially hollow, rounded body, they are normally found in limestone and are characterized by an outer layer of dense chalcedony and an internal cavity which may be partly or wholly filled with inward-projecting crystals.
Geological Survey Branch
A part of the British Columbia Ministry of Energy, Mines and Petroleum Resources which carries out geological mapping and scientific research. Information collected by the geologists who work for the branch is used for environmental, land-use and mineral development activities in the province.
Geology
The study of the earth and planets, the materials of which they are made, the processes that act on these materials, the products formed and the history of the planet and its life forms.
Glacial Deposits
Material which was laid down as sediments or debris by glaciers, this normally includes gravels and sands.
Gneisse
A banded, or foliated, rock formed by heat and pressure.
Granite
A term loosely applied to any light-coloured, coarse grained plutonic rock containing quartz, as a major component, with feldspar and dark minerals. Plutonic rocks are those which cool beneath the earth’s surface over a long period of time and which therefore tend to be composed of coarse sized mineral crystals.
Gullies
Depressions formed in the landscape by streams and creeks eroding soils, gravels and suricial sediments.
Gypsum
The commonest sulphate mineral, CaSO42H20, frequently associated with halite (salt) and anhydrite in evaporates (sediments formed by evaporation of water) Gypsum is very soft, white or colourless but commonly has grey, red or brown tints. It is used to make plaster of paris.
Idocrase
Idocrase, or vesuvianite, is a brown, green or yellow mineral found in limestone’s which have been “baked” by hot intrusive rocks, also known as “California Jade.”
Igneous Rocks
Rocks which are formed by molten magma either at or below the earth’s surface.
Intrusive
Rocks which intrude or cut across other rocks. They normally “intrude” these other rocks as molten magma and then cool to form volcanic or plutonic rocks.
Jade
A hard, extremely tough, gemstone consisting of the pyroxene mineral jadeite, or the amphibole mineral nephrite, may range in colour from dark-to-deep green to a dull or greenish white. It takes an excellent polish and is used for jewellery and carved articles. “California Jade” is a compact from of vesuvianite.
Jasper
A variety of chert associated with iron ores, characteristically red by yellow, green, brown and black varieties are known.
Kyanite
A blue or light green mineral which occurs in long, think bladed crystals in schists, gneisses and granite pegmatities.
Lava
Hot, molten rock which has been forced out upon the surface of the earth and which normally flows like molasses downhill.
Limestone
A sedimentary rock consisting chiefly of calcium carbonate, limestone is formed by a variety of processes, most notable they are created by the organisms which build coral reefs in relatively shallow ocean waters.
Lustre
The reflection of light from the surface of a mineral described by its quality and intensity, terms such as metallic or resinous, bright or dull may be used to describe the lustre of a mineral.
Magma
Rocks which are molten liquid due to high heat and pressure.
Marble
A metamorphosed limestone in which the calcium carbonate has become crystallized and will polish well.
Metamorphic Rocks
Rocks which are changed by pressure, temperature or chemicals to form new types of rocks. This normally means that the minerals which compose one rock type are re-crystallized to form new minerals.
Micro-continent
A small independent group of rocks which may be transported and welded into a larger continent, British Columbia is composed of many “micro-continents” which have been attached to the western edge of North America. Modern-day examples could be Vancouver Island or the Queen Charlotte Island’s which are being transported towards the mainland and (in several million years) will actually become part of it.
Mine dump
The waste rock, or gangue, left over from the mining operation, usually the ore, or mineral of value, is extracted from the rocks and the waste is piled up as a mine dump.
Mineralogy
The study of rock forming minerals.
Mineral
A naturally occurring, inorganic element or compound having an orderly internal structure and characteristic chemical composition, crystal structure, and physical properties.
Muriatic Acid
This is a common term for hydrochloric acid.
Muscovite
A member of the mica family of minerals, it is similar to biotite.
Nodule
A fragment of coarse-grained igneous rock which is enclosed within another extrusive or intrusive igneous rock.
Outcrop
A geologist’s term for the area in which rocks are exposed a the earth’s surface.
Palaeontology
The study of life and its environments in past geologic time based on fossil plants and animals.
Pegmatitie
Very coarse grained plutonic rock similar to granite in chemistry but characterized by very large mineral crystals. Some pegmatites have feldspar, quartz or other mineral crystals up to a metre or more in size.
Petrology
A branch of geology which deals with the origin, occurrence, structure, and history of rocks.
Properties
The characteristics of rocks or minerals by which they may be identified.
Prospected
The process or activity by which a geologist or prospector examines and evaluates an area for valuable minerals.
Pry Bar
A crow-bar which can be used to free minerals from their host rocks.
Quartz
An important rock-forming mineral composed of silica.
Rake
Rake or pitch is the angle between the horizontal and any linear feature along the direction of the linear feature.
Rhodonite
A pale-red or rose-red mineral of the pyroxenoid group of minerals, it is commonly used as an ornamental stone and polishes well.
Road Cuts
An excavation along or through a hill which is used to build a road.
Rock Identification Kit
A kit composed of the tools and materials needed to test rocks and minerals to determine their properties. Typically such a kit would include a knife, a streak-plate, weak hydrochloric acid, a magnifying lens and a magnet.
Rutile
A reddish-brown mineral which commonly occurs in quarts (e.g. rutillated quartz), in large concentrations it may be an ore of titanium.
Schist
A strongly foliated crystalline rock which can be readily split into flakes or slabs.
Sedimentary Rock
A rock which has resulted from the consolidation of loose sediment that has accumulated in layers.,examples are sandstone, shale, conglomerate an siltstone.
Serpentine
A group of rock-forming minerals which have a greasy or silky lustre, a soapy feel and which are usually dark green to black in colour.
Sillimanite
A mineral which occurs in long, slender needle-like crystals.
Soapstone
A metamorphic rock composed essentially of talc which is used extensively for carvings and jewellery.
Spinel
A very hard, gemstone, varies widely in colour from colourless, to purple-red, green and black.
Spodumene
A white-to-green prismatic mineral which may occur as very large crystals in pegmatities.
Staurolite
A brown-to-black mineral crystal, twinned crystals are common and form the shape of a stubby cross.
Streak
The characteristic colour a mineral leaves when rubbed across a streak plate (a streak-plate is a white, non-glossy, ceramic tile).
Topographical Map
A map of an area showing the hills and valleys by using ‘topographic contour lines”, it usually also contains much information on roads, rivers, towns and other features you may come across in a given area.
Topography
The general shape of the surface of the earth particularly used to define to the shape of the hills and valleys.
Tourmaline
A dark brown-to-black mineral which occurs as 3, 6 or 9 sided, elongated prisms, the prisms are characteristically striated along the long axis of the crystals.
Travertine
A dense, finely crystalline limestone which may be white, tan or cream in colour, usually formed around hot springs or in limestone caves, a less compact variety is called tufa.
Vein
A thin, sheet-like fracture in a rock which is filled with secondary minerals such as quartz or calcite.
Wollastonite
A metamorphic mineral found in altered limestone.
Zeolite
A large group of white or colourless hydrous aluminosilicate minerals, commonly filling cavities in basalt lavas.
