Alters  to  malachite  according  to  the  following  reaction :

2[2CuCO3.  Cu(OH)2]  -|-  H2O  -f  CO2  =  3[CuCO8.  Cu(OH),].
Formation  and  occurrences  same  as  for  malachite.  Excellent  crystals
occur  at  Chessy,  France ;  Cornwall,  England ;  Ural  Mts. ;  Chile ;  Australia ;
Bisbee  and  Clifton  Copper  districts,  Arizona ;  also  in  Utah,  California,  etc.
An  ore  of  copper.  Paint  made  from  azurite  turns  green  in  time,  due
to  an  alteration  to  malachite,  see  above.
HYDROCERUSSITE,  2.PbCO3.  Pb(OH)2.
Hexagonal,  dihexagonal  bipyramidal  class,  a  :  c  =  i  :  1.4187.  Occurs  as  color-
less plates  on  native  lead  at  Langban,  Sweden ;  with  galena  at  Wanlockhead,  Scotland.
HYDROZINCITIV,  Zinc  Bloom,  ZnCO3.  2Zn(OH)2.
Crystal  form  is  unknown.  Only  in  compact,  earthy,  or  fibrous  masses ;  some-
times reniform,  stalactitic,  or  in  crusts.  Somewhat  brittle.  Hardness  2  to  2.5.  Spe-
cific gravity  3.25  to  3.8.  Color  is  snow  white  to  yellowish.  Vitreous  luster.
ZnCOs.2Zn(OH)2.  Composition  is  not  constant.  Hydrozincite  is  an  alteration
product  of  rdnc  minerals.  Hence,  is  found  with  hemimorphite,  smithsonite,  sphalerite,
etc.  Occurs  at  Bleiberg  and  Raibl,  Carinthia ;  various  places  in  the  province  of  San-
tander,  Spain ;  Sardinia ;  Algeria ;  Friedensville,  Penna ;  Linden,  Wis.
AURICHALCITE,  2(Zn.Cu)CO3-3(Zn.Cu)  (OH)2.
Monoclinic,  prismatic  class,  a  :  b  :  c  =  ?  :  i  :  1:657,  £  =  84°  15'.  Acicular
crystals,  also  rosette  aggregates.  Hardness  2.  Pale  green  to  sky-blue  in  color.
Pearly  luster.  Translucent.  May  contain  as,  much  as  8%  CaCOs,  and  is  then  known
as  buratite.  Occurs  with  limonite  and  calcite  at  Loktewsk,  Altai,  Siberia;  Chessy,
France;  Lancaster,  Penna.;  Santa  Caterina  Mts.,  Arizona;  Beaver  Co.,  Utah.
DAWSONITE,  Na.Al(OH)2CO3.  Occurs  in  thin  lamellar,  and  fibrous  aggregates.
White  in  color.  Vitreous  luster.  Specific  gravity  2.40.  Found  in  a  feldspathic  dike
at  Montreal,  Canada;  also  in  a  cinnabar-bearing  dolomite  in  Tuscany.
