Pseudomorph

A pseudomorph (from Greek, meaning 'false form') is a mineral whose external crystalline form is that of another mineral. This occurs when a mineral undergoes alteration or replacement by another, while retaining the original mineral's shape. The process involves a change in the mineral's chemical composition, often through the introduction or removal of elements, but the existing crystal structure provides a template for the new mineral's growth. Pseudomorphs provide valuable insights into geological processes, indicating past mineralogical transformations and the conditions under which they occurred.

Pseudomorph meaning with examples

• The calcite pseudomorph after aragonite showcased how the original aragonite crystal shape was perfectly preserved while the mineral composition changed to calcite. This delicate transformation offered a look into the unique conditions of mineral formation at the specific location.
• Examination of the pyrite pseudomorph after marcasite revealed identical crystal habits even though the iron sulfide had transformed. Careful analysis of the pseudomorph provided the key understanding on the chemical reactions responsible for the alteration.
• During the field trip, we found a quartz pseudomorph after a specific type of feldspar. The sharp edges of the pseudomorph suggested it was in a state of transition after the original minerals, suggesting conditions had changed significantly after its formation.
• The gemstone cutter studied a malachite pseudomorph after azurite. The change of colour and unique crystal shape revealed important clues about the mineral formation within the mine that revealed new facts about how minerals change overtime.
• Scientists analyzed a pseudomorph sample of limonite after pyrite. The rusty-coloured, often porous pseudomorph, provided direct evidence of oxidation processes that had converted pyrite into limonite under specific conditions during the rock formations.