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  • It's somewhere between 5.5 and 7 on the hardness scale
  • Feels very heavy
  • Cold to the touch
  • Doesn't clean up with water, vinegar or alcohol
  • Small bumps on the surface all over

enter image description here

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  • $\begingroup$ Hi. Please read this guide and add as much information as you can. Pay special attention to the streak (my spidey sense says it will be red) and whether it's a little magnetic or not. $\endgroup$ – Spencer Feb 9 at 2:31
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    $\begingroup$ Given that Charmouth is close to Lyme Regis & that Lyme Regis once had a cement industry it could be a lump of cement. $\endgroup$ – Fred Feb 9 at 13:41
  • $\begingroup$ the first thing i think of when i see this is a stromatolite,if it had been cement it had reacted with vinegar,i know a little about cement and concrete after 35 years of working with it. $\endgroup$ – trond hansen Feb 11 at 18:46
  • $\begingroup$ cement is not very heavy. limonite is magnetic when heated. $\endgroup$ – com.prehensible Feb 13 at 10:33
  • $\begingroup$ It could be hematite too. Does it leave a redish or a brownish streak? $\endgroup$ – Universal_learner Feb 13 at 17:10
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It is probably limonite:

There are lots of different varieties of limonite, some of them are like that one which has heamatite spherule concretions, globular heamatite, nodules, blueberries, they have even been photographed by a Mars rover: enter image description here

utah: enter image description hereenter image description here enter image description hereenter image description hereenter image description here

http://www.assignmentpoint.com/science/physics/limonite.html

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