Hi Noah
Maybe at Jennifers Location is no Calcite and so the Environment ist to acidic to form Malachite.
Yes, that will be the case, due to much decomposing pyrite, mainly. So why just pyrite?
The pyrite is composed of Fe and S in the ratio of 1:2. The most oxydated product of weathering is iron(III)sulfate with a ratio of 2:3. With other words, pyrite contains more S than be bound by the contained iron. The overstanding S causes an acidic environment.
As to the equations you asked for
First let us use an other scription
for malachite CuCO
3*Cu(OH)
2for azurite 2CuCO
3*Cu(OH)
2Both are composed compounds of copper carbonate and copper hydroxide.
Copper carbonate can be formed from copper sulfate and calcite
CuSO
4+CaCO
3 <-> CuCO
3+CaSO
4Copper carbonate decomposes hydrolytic
CuCO
3+H
2O <-> Cu(OH)
2+CO
2This equations can run in both directions and are in an equilibrium state. According to the rules of the lae of mass action a low pH value and/or a high concentration of CO
2 shift this equilibrium to the left side and prefers the forming of azurite.
Thomas