. ▁This ▁includes ▁a ▁range ▁of ▁pre - cut ▁pieces ▁ready ▁for ▁in lay ing ▁into ▁the ▁black ▁mar ble ▁background . ▁Items ▁such ▁as ▁forget - me - not ▁and ▁l ily ▁of ▁the ▁valley ▁flowers ▁would ▁typically ▁be ▁represented . ▁Col oured ▁rocks ▁to ▁in lay ▁into ▁the ▁black ▁" mar ble " ▁included ▁grey , ▁blue ▁and ▁pur ple ▁min er als ▁locally ▁from ▁M ony ash , ▁" rose wood " ▁from ▁N ett ler ▁D ale ▁in ▁Sh eld on ▁which ▁consisted ▁of ▁red ▁and ▁white ▁layers , ▁b ary tes ▁which ▁created ▁other ▁variations , ▁the ▁local ▁Cast leton ▁Blue ▁John ▁which ▁could ▁create ▁pur ple , ▁and ▁yellow ▁fl ours par ▁from ▁C rich , ▁whilst ▁" B ird s - E ye " ▁rock ▁had ▁a ▁design ▁made ▁from ▁the ▁foss ils ▁that ▁it ▁contained . ▁The ▁r ar est ▁min eral ▁was ▁known ▁as ▁" D u ke ' s ▁Red " ▁and ▁this ▁was ▁so ▁valuable ▁that ▁it ▁was ▁stored ▁at ▁Ch ats worth ▁House . ▁The ▁table top ▁design ▁illustrated ▁shows ▁some ▁of ▁the ▁combinations ▁described ▁here . ▁ ▁In ▁the ▁late ▁ 1 7 8 0 s ▁Derby shire ▁ge ologist ▁White ▁Watson ▁began ▁to ▁create ▁explan atory ▁ge ological ▁table ts ▁using ▁Ash ford ▁Black ▁Mar ble ▁into ▁which ▁other ▁local ▁rocks ▁were ▁in la id ▁so ▁as ▁to ▁represent ▁the ▁str ata ▁of ▁the ▁rocks ▁in ▁different ▁parts ▁of ▁the ▁county . ▁Derby ▁Museum ▁has ▁a ▁diagram ▁of ▁E