The reason why I created the magnetic gem and mineral float tester:
I purchased a box full of used Silversmithing tools and in the bottom was a
collection of gems and minerals. I needed a helpful diagnostic tool to
identifying and sort my new found collection. I read on several ways of testing
using commercial equipment. Since this is a hobby, I decide to read further on
alternative ways to test them. I came up with my version of a magnetic float
tester. Using the magnetic affects on the specimen floating on a water surface,
to identify the specimen.
Why gem and minerals are magnetic: Some gems and minerals are magnetic due to the metals contained in them. Gems and minerals can be attracted or repelled by a magnetic field. The level of observable attraction can be noted as minimal, moderate, and maximum. Gems and minerals can be divided and recognize by observing the range of the responsiveness they demonstrate when the magnetic field magnet is applied to them.
Step 1: Items Used
– capable of being cut to length
· Household scissors
· Drill press
· Drill bit 25/64 (3/8 could also be used)
· Circular surface level (levels in all directions at once)
· Miter box or good eyes
· File – made for metal fine tooth
· Deburring tool
· Finger nail polish – I used yellow to match painted aluminum
· Large 1-inch metal paper binder clips
· Threaded furniture glides (come in sets of 4) size = 1 – 1/16 threaded glides only need three
· 6-foot aluminum level – cut to 8 inches
· Float chamber clear water tight plastic 1 ½ inches wide - 4 inches long - 3/8 inches deep
· Tweezers plastic (metal is shown, plastic would work better)
· Two water tight containers – large enough to fill float chamber – I used plastic film canisters 1 ¼ inches in diameter by 2 inches tall. One is just for storage of borax the other to contain the mixture of water and borax. The volume used was 1 tsp (teaspoon) or 15 ml.
· Small spoon – used to scoop the borax
· Plastic wand – used to push foam
· Dense cell plastic foam – enough to make a few 1 x 1 x 3/8 thick inch squares, this foam must be capable of floating and not retaining water.
· Eyedropper – if float chamber is too full of mixture used to draw liquid out.
· Rare earth magnet – 11/16 diameter 1/8 thick coin size
· Helping hands
· 3 by 5 index card plastic box
Step 2: Reduce Water Surface Tension
I wanted the specimen to move freely in their reaction to the magnet. I am using a water chamber with a foam float. While working on another project, I found out a neat trick in reducing the water surface tension; by adding simple
borax to the water.
What I used for borax mixture:
Two water tight containers – large enough to fill float chamber – I used plastic film canisters 1 ¼ inches in diameter by 2 inches tall. One is just for storage of borax the other to contain the mixture of water and borax. The volume of water used was 1 tsp (teaspoon) or 15 ml. This allowed room to shake to mix the borax and water.
Small spoon – used to scoop the borax
Please note: the picture shows the borax used. the film canisters can be seen in later steps.
Water - filter or spring.
Step 3: Foam
Not all foam is designed or made the same;some foam will actually collect water. For this application, I needed dense
cell plastic foam that must be capable of floating and not retaining any water.
I found inner box packaging foam used to hold parts safely in a box (not Styrofoam). The one I found/used has a waxy feel to it.
Using household scissors I cut a few 1 x 1 inch squares (I averaged 3/8 inch in thickness) ; cut enough to make extras. In order for the specimen to set well or set flat, some shaping is required. I made indents in the middle of the extras to take the various shapes.
Step 4: Make the Base
I really like working with aluminum I-beams, it has great strength and versatility. I purchased a discount 6-foot
aluminum cement workers level. This gave me several areas to cut out a usable section
(without a level bubble or a hole). In addition, for the levels cost, I can cut out several
sections to use on other projects.
I used a hacksaw and miter box to cut the I-beam to 8 inches. My apprentice and I worked out in the 20 degree Fahrenheit barn. After cutting, a metal file was used to debur the ruff cut ends. To make the ends look a little better, I used yellow nail polish. This not only looks better, it gives a nice smooth finish. This tester is intended to be picked up, so a good finish is needed.
I made a spacing template out of an index card. I used a hole punch on the card, so I can use a black marker to transfer the spacing onto the I beam. Once I marked two holes on end, I kept the same distance from the end and made a single mark in the middle of the other end.
After marking, I used a center punch on the holes to prepare for drilling. The call out for hole diameter for the threaded furniture glide inserts was 3/8. I choose to drill a larger diameter of 25/64 inches. I used my Deburring tool to clean the drilled holes.
Note: I plan on using this tester at different locations, which will have different surfaces. This is why I used the three legged milking stool design for the legs. Three legs provide speed and ease of leveling.
Step 5: Add Legs to Base
I reversed the plastic threaded insert from the original design intentions. The reversing creates an almost flush button. I needed the
lower protrusion to allow the magnetic slide base to slip into position between
Note the rails have a slight rib on the top, preventing a direct drop in of the magnetic slide base.
Step 6: Add Indexing to I-beam Base
I found a nice rubberized ruler to act in the indexing, for the float and magnetic
base. I used household scissors to cut the blue ruler to match the length of
the Yellow base. I used two large 1-inch
metal paper binder clips to hold the ruler. The nice thing about the yellow
base being an I-beam, it allows multiple ways of mounting things to in.
The blue ruler actually fit flush to the bottom rail to just revealed the metric marks and numbers above the top rail. I will not take credit for this clean look; I call it just plain luck.
I removed the binder clip handles to make even cleaner look.
I keep them in the index card storage box.
Step 7: Magnetic Slide Base
It is my understanding that all natural substances respond to a magnetic field. The specimen response is either an attraction or being repelled. These responses were once very difficult to be seen by the naked eye. The old horseshoe style magnets are so much weaker than rare earth magnets. In attempt to amplify the magnetic field, I choose to use a coin size rare earth magnet. Rare earth magnet used is a 1 1/16 inch diameter 1/8 inch thick coin size.
I wanted something that would fit between the rails of the aluminum base I-beam. I also wanted something that could extend out over the floating chamber. Again, I lucked out. I made the slide base out of a helping hand. I striped off everything but a flex joint and a ball joint extension.
The base is nice and heavy not to tip over when the magnet is extended. The helping hands I found had a nice felt bottom, the sliding action was perfect.
Assembly is by just adding the magnet to the end of the ball joint extension.
Step 8: Floating Chamber
The Floating chamber needs to be clear and water tight plastic. It also has to long enough to allow the float to
move to or away from the magnetic slide base. I looked at several different off the shelf
containers. I wanted it to fit between the 2-inch span between the rails of the
base. I wanted clear to help see the movement of the specimen.
I came up with a 1 ½ inches wide - 4 inches long - 3/8 inches deep plastic cover. I came off a medical product. It fit all my dimensional requirements, but actually, the walls are too thin. It functions well but, when I go to throw the water away, it can flex and spill.
My hunt for a ridged plastic of this size is still on.
Step 9: Leveling the Base and Putting It All Together
I found a solid surface to set up the tester. Then I used the circular surface level (levels in all
directions at once) in the middle of the yellow I-beam base, along with the assembled Magnetic slide base. Once leveled, I
put the Floating chamber on top of the base.
Then I made the water borax mixture. For the mixture I used a plastic film canisters to mix water and borax. The volume used was 1 tsp (teaspoon) or 15 ml of water and small spoonful of borax. This allows room to shake and mix the borax and water.
The borax mix ratios I found on the internet, were created for very large volumes. I felt that even though I could calculate down the ratio, I was not sure if the calculated mixture would be effective at the lower volume (I was plan on using). Therefore, my thought process is it is better to be consistent from batch to batch.
I used the small spoon to scoop add the borax to the water. I found if you add borax first, it tends to clump on the bottom and it takes more energy to dissolve.
I pour the water borax mixture into the floating chamber.
I added the foam and now it is ready for testing.
The eyedropper is if float chamber is too full of water borax mixture and is used to draw the liquid out.
Step 10: Testing the Tester
Gems and minerals can be attracted or repelled by a magnetic field. The level of observable attraction or repell can be noted
as minimal, moderate, and maximum. Gems and minerals can be divided and
recognize by observing the range of the responsiveness they demonstrate when
the magnetic field magnet is applied to them.
Some fancy words:
Ferromagnetism: means an item that exhibits maximum attraction to magnetic fields.
Paramagnetism: means a item that exhibits minimal attraction to a magnetic fields but can become Maximum Magnetic when they are heated.
Diamagnetism: means an item is repelled from magnetic fields.
My first test specimen was I believed to be Citrine. It supposes to have a minimum attraction. I did not detect any movement.
The second test specimen was a garnet; which is known to be a maximum attraction. Well the specimen I had move towards the magnet. Maximum attraction.
I am very pleased with the design and outcome of my Magnetic Gem & Mineral Float Tester