Hi Eu I get what you're saying about limonite so had a look at a lot of images and a read and limonite should have a yellowish streak, so had another streak test on my rock and pressed a lot harder and you really have to look hard to see the slightest faintest of any mark so much I would say no streak really, and cant find an image like my rock, and tried scratching white part and brown part with a very sharp point of blade and no marks on either part of rock, to be honest there's a lot more detail to rock when looking closely with microscope, the piece I have at museum is of same rock but has visible bright metal pieces in it but its been in museum in Cambridge since Jan and hasn't been looked at yet, perhaps it's been binned.
Looked at lots of rock and pics but cant find a match for this rock,white part look like it's made of the tiniest white particles held together with a slightly transparent resin and has a sheen to it, the crust is reddish/brown cracked and you can see where the previously fractured sides have a thin covering of the crust, underneath the crust is an orangey/brown toffee looking rock with a grey looking rock underneath the orange part, in the orange and grey part there's the tiniest mix of coloured grains i.e. black pink cream white brown & a bluish/grey, there is also same grains in some areas of the white part which looks like a porridge mix, looks very organic strangely, I guess the outside must have hematite in it but doesn't show on a streak test unless a lot of pressure is applied but then only a faint pink, moves with a magnet but doesn't pick up although I have piece at museum that has lots of bright metal in and clicks to magnet and another piece that has tiny bit of crust with holes like slag, most of what said can only be seen with magnifying glass, there is also a few clear yellowish bits and I don't believe white part is quartz as cant find rock similar,
