▁ 1 9 8 2 . ▁The ▁two ▁senior ▁authors ▁sample d ▁peculiar ▁ve ins ▁and ▁enc rust ations ▁of ▁crypt oc ry st all ine ▁fine - gra ined ▁white ▁material . ▁One ▁of ▁the ▁materials ▁had ▁properties ▁which ▁could ▁not ▁be ▁matched ▁to ▁any ▁known ▁min eral . ▁▁ ▁The ▁min eral ▁occurs ▁closely ▁with ▁z ah er ite , ▁Al 1 2 ( SO 4 ) 5 ( SO 4 ) 3 ( OH ) 2 6 . 2 0 H 2 O . ▁ ▁Phys ical ▁properties ▁ ▁Hot son ite ' s ▁physical ▁properties ▁are ▁similar ▁to ▁other ▁hyd r ated ▁al umin ous ▁sul f ates ▁and ▁some ▁ph osph ates . ▁It ▁occurs ▁as ▁a ▁white ▁ch alk ▁like ▁min eral ▁with ▁a ▁d ull ▁to ▁sil ky ▁l uster , ▁and ▁an ▁earth y ▁f ract ure . ▁When ▁observed ▁under ▁magn ification ▁of ▁ 5 0 0 ▁times , ▁it ▁has ▁a ▁fla ky ▁appearance . ▁Hot son ite ▁appears ▁with ▁a ▁white ▁color ation , ▁and ▁small ▁gra in ▁size . ▁The ▁Moh s ▁hard ness ▁is ▁▁ 2 . 5 , ▁and ▁with ▁a ▁density ▁value ▁of ▁ 2 . 0 6 0 ▁to ▁ 2 . 0 6 8 . ▁ ▁Chem ical ▁composition ▁The ▁chemical ▁analysis ▁was ▁carried ▁out ▁using ▁X - ray ▁flu ores c ence , ▁and ▁the ▁water ▁was ▁calculated ▁by ▁the ▁Pen field ▁method . ▁ ▁D iff raction ▁information ▁ ▁Pow der ▁diff raction ▁used