2 May 2017 at 6:41 pm #573741Dr James DawsonParticipant
Talking to Bob Mizon at the recent Eastbourne meeting of the British Astronomical Association as he manned the Commission for Dark Skies stand, the topic of meteorites came up and the fact many have a significant metallic content. He had some on show and a magnet and sure enough the meteorites were attracted to the magnet. He explained that as an outreach activity he had asked people to bring in the sludge out of their gutters, and in the experiment mixed the sludge with water in a jam jar and wafted a magnet around in the water to attract the metallic fragments. These fragments may well have come from outer space as part of a meteorite. This idea excited me, and as one who loves to experiment I couldn’t wait to get home and rummage in my gutters.
Luckily I have some gutters at the front of the house around the porch so can easily access them with a normal step-ladder; don’t do this if you have to go very high for sludge, ask the window cleaner to get the sludge for you or rummage in someone else’s gutters after gaining their permission.
I got about 250g of stuff in total out of the gutter (I’d cleaned them pretty well about three years ago). I mixed the sludge with water and introduced the magnet; I pulled out a reasonable amount of ferromagnetic stuff (my scales don’t weight such small amount) but image below comparing the stuff to a 5p coin.
I’d already ordered a USB microscope off the internet (https://www.amazon.co.uk/COLEMETER-Handheld-Microscope-Magnifier-Endoscope/dp/B00TJYS9AG/ref=sr_1_2?ie=UTF8&qid=1493745622&sr=8-2-spons&keywords=usb+microscope&psc=1 – other retailers and options available), so once it had all dried I looked at it under the microscope.
There was a mixture of flakes of things, round pebble like things of differing colours (imaged), and what looked like conglomerate bodies with various textures and densities and numerous inclusions (imaged). The was also one silvery shiny body (imaged). The larger bits were 1.5mm to 2mm in size (imaged) – the black lines are 0.5mm apart.
So I have no idea if these are meteorite fragments or not, but it is still fascinating and has been a fun exercise. What’s more, my gutters are now spotless!
Attachments:2 May 2017 at 9:11 pm #578179MARC TRYPSTEENParticipant
To check if your “Gutter collection” contains possible meteorites you can try following tests:
1. Native Iron test: a magnet is attracted. This test was apparently positive.
2. Streak test: Therefore you scratch the rough side of ceramic material ( such as an old bathroom tile). If negative, this means if no streak (colored or not) is visible, it is a vote for a meteorite.
3. DMG test or Nickel test. This can be done qualitatively bij etching a part of the material with an acid solution (Nitric acid or Hydrochloric acid 1% solution in water). Afterwards you rub the stone with a solution containing 1% DMG (Dimethylglyoxime) in alcohol with 10% ammoniumhydroxide. (available at local pharmacies or on line shops). If positive means a red color is appearing. You may then go to a specified lab to do a quantitative test to determine the % Nickel.
4. Estimate the density of the rock: first weigh it on an analytical balance (ask local pharmacist), then put it in a measuring cilinder filled with water, put the rock in it and calculate the difference of the water level. Calculate density which is mass divided by volume. Depending on the type of meteorite this gives 3.5 to 4.5.
If all tests are positive go to a university lab for detailed analysis!
Marc.3 May 2017 at 6:41 am #578181Dr James DawsonParticipant
This is very helpful and useful to know. My fragments are too small to rub on anything I fear but at least I now know what to do if I find something bigger.
James3 May 2017 at 8:15 am #578182David BaseyParticipant
The article here may be of interest. It includes links to a number of other resources including the original professional paper.
David.3 May 2017 at 9:00 am #578183MARC TRYPSTEENParticipant
No problem, James, if the pieces are too small to rub you can follow an alternative procedure: pulverize some pieces to obtain approx. 1 or 2 grams of powder, put it in a glass test-tube or anything similar. Add slowly the acid solution (Nitric acid or Hydrochloric acid 1% aq. solution) to solve the powder. Then add ammonium hydroxide solution (10%) to make alcaline. In case Iron is present you will see a brown-yellowish precipitate which is mainly composed of Iron hydroxide. After filtering add some droplets of a DMG solution (1%in alcohol) to the filtrate: if meteorite material is present you will see a reddish colored precipitate.
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