During my previous vacation in India, I noticed dark streaks in the sand while walking on the beach, which piqued my interest. During a subsequent research, I came across this phenomenon. The idea for this earth cache was born.
Iron sand is colloquially a sand enriched with heavy minerals that has a high proportion of iron minerals. The color of the sand is dark gray or blackish. The predominant iron mineral in the sand is magnetite Fe3O4, whereby the pure iron content can be between 54% and 60% depending on the location and quality. In addition, other mineral compounds can also be present, such as. B. titanium (IV) oxide TiO2, vanadium (III) oxide V2O3, magnesium oxide and others.
After aluminum, iron is the most common metal in the earth's crust. Due to volcanic activity, it can be transported in relatively large quantities from the deeper areas of the crust or from the upper mantle to the earth's surface, where it becomes part of the lava rock in the form of iron minerals. Millions of years ago, areas with ferrous rock were created in different parts of the world and then eroded over long periods of time.
Source: https://de.wikipedia.org/wiki/Eisensand
Iron sand occurs almost everywhere in the world. However, it is only rarely found in economically significant and degradable quantities (e.g. in Chile, Guatemala, Indonesia, Canada, Japan and New Zealand). The small but heavy stones or grains were distributed along the coasts by wind, waves and tides. Due to their higher specific weight (5,2 g/cm3) than normal (quartz) sand (2,65 g/cm3), they were concentrated.
Can you filter magnetic sand?
Yes, even very simple. All you need is a sheet of paper, a magnet and a small vessel. Hold the sheet of paper over a spot with dry (!!) sand and slowly approach it with the magnet. Now move the leaf back and forth a little over the sand. Then you hold the sheet over a vessel and remove the magnet. The mineral now falls into the vessel without any residue remaining on your magnet.
To log this earth cache,
Now go to the "Lighthouse Beach". The listing coordinates are in the middle of the beach and are irrelevant for answering the questions. All you need for the experiments is a magnet, a piece of paper and possibly a small box / plastic bag for later samples at home. Then deal with the three tasks below. You don't have to be a geologist for this - your comprehension and observations on site are completely sufficient. Task three can be answered with a little housework without too much trouble.
1. Look for dark spots in the area where the waves gently wash the sand. Now filter the sand as described above and look at the sample. Can you see different colors? Please add pictures of the filtered parts to your log.
2. Take a closer look at the beach section. Are there places where the iron sand is concentrated? If so, how do you explain it to yourself?
3. Take a photo of yourself or a personal item with the Lighthouse in the background. According to the guidelines of June 10, 2019, this is an acceptable log condition. Logs in which the photo is not attached will be deleted without comment after a period of 14 days.