Borax and Tincalconite
Chemical Formulas:
Borax: Na2B4O7 •10H2O ~ Hydrated Sodium Borate
Tincalconite: Na2B4O7•5H2O ~ Hydrated Sodium Borate
Look closely at the chemical formulas for borax and tincalconite. You will see that they are almost exactly the same, EXCEPT that tincalconite has 5 fewer molecules of water in its formula than does borax. As borax sits out in a dry environment, water molecules actually escape from the crystal structure. Tincalconite is a white, powdery mineral. As borax crystals lose water and turn into tincalconite, they start to get soft and fall apart. Eventually the crystals will fall apart into a pile of tincalconite powder. Because of this, it takes some work and special preparations to be able to keep and preserve borax crystal specimens.
Borax crystals quickly begin to lose water and turn into tincalconite. “Borax” specimens that you will see at shows and mineral shops have already begun to change into tincalconite, at the very least on the surface. As the borax crystals become tincalconite, they still have the form (that is, the shape) of the original borax crystals. The name, tincalconite, comes from the Sanskrit word tincal which means borax and the Greek word konis which means powder. Extremely large crystal groups of borax/tincalconite have been recovered from Death Valley.
It is not unusual in the mineral kingdom for one mineral to chemically change into another while keeping the shape of the original mineral. The result is what mineralogists call a pseudomorph which means false form. Another example of pseudomorphs found in California are azurite crystals that changed into malachite.
Chemical Formulas:
Borax: Na2B4O7 •10H2O ~ Hydrated Sodium Borate
Tincalconite: Na2B4O7•5H2O ~ Hydrated Sodium Borate
Look closely at the chemical formulas for borax and tincalconite. You will see that they are almost exactly the same, EXCEPT that tincalconite has 5 fewer molecules of water in its formula than does borax. As borax sits out in a dry environment, water molecules actually escape from the crystal structure. Tincalconite is a white, powdery mineral. As borax crystals lose water and turn into tincalconite, they start to get soft and fall apart. Eventually the crystals will fall apart into a pile of tincalconite powder. Because of this, it takes some work and special preparations to be able to keep and preserve borax crystal specimens.
Borax crystals quickly begin to lose water and turn into tincalconite. “Borax” specimens that you will see at shows and mineral shops have already begun to change into tincalconite, at the very least on the surface. As the borax crystals become tincalconite, they still have the form (that is, the shape) of the original borax crystals. The name, tincalconite, comes from the Sanskrit word tincal which means borax and the Greek word konis which means powder. Extremely large crystal groups of borax/tincalconite have been recovered from Death Valley.
It is not unusual in the mineral kingdom for one mineral to chemically change into another while keeping the shape of the original mineral. The result is what mineralogists call a pseudomorph which means false form. Another example of pseudomorphs found in California are azurite crystals that changed into malachite.
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