GUIDELINES FOR THE CURATION OF GEOLOGICAL MATERIALS

published data on these (see King 1982, 1983; Sinkankas 1972; Waller 1980 and in
press).
In general those minerals that formed in surface or near surface aqueous
environments are also the most soluble and most sensitive to alteration by
hydration or dehydration.
Both hydrous minerals and those containing loosely bound water molecules can
deteriorate so rapidly and so intractably as to become worthless. Sealing in
containers to retain or exclude moisture is often only partially or temporarily
successful, because the phase stability is outside those conditions that can
normally be achieved in the museum.
The following groups are vulnerable to washing in water:
Sulphates. Most of the simple sulphates (with the fortunate exception of several
of the commonest) of sodium, potassium, magnesium, zinc, copper, aluminium,
iron and manganese. These are both soluble and liable to hydration state
changes.
Carbonates. Those of sodium and potassium are most vulnerable.
Nitrates. A small group, vulnerable to hydration changes, and also soluble.
Fig. 10. A fine example of baryte crystals on a dolomite groundmass. The specimen
measures 20 X 12" X 12", is very heavy and requires careful handling and support. The
lustrous baryte crystals are soft and possess good cleavage, so dust accumulations, poor
storage or rough handling could easily cause damage. The specimen came from the
Goosegreen Mine, Frizington, Cumberland (Cumbria) and was aquired in 1899 by the
Department of Mineralogy, British Museum (Nat. Hist.) and is number BM 84006.