This is a fragment of a talc imprecation cursing an opponent in a court dispute. It is dated to the third to fourth century and was part of a group of multiple fragments. The material chosen for the curse is selenite, which is very rare in contexts of ancient magic.
The joint fragments form an inscription aiming to affect a lawsuit between Timokrates and Theodosios.
The following comment is a quote from the artefact’s website of the British Museum London:
The fragments were said to have been discovered in a deep shaft containing bones during the digging of a well. In the GR Register, the tablets were attributed to ‘Curium’ (i.e. Kourion (q.v.)), a provenance repeated for over a century in publications. However in the Register ,‘Curium’ was subsequently crossed out and replaced with ‘Agias Tychonas’ (i.e. Ayios Tychonas), though the source of the revised information is not stated. However, the latter area is likely to be correct as some of the BM fragments join with tablets in Paris which are said to come from Amathus. It is likely that the name of the modern village was confused with the ancient site located on the coast to the south, or that the discoverers/vendor lived in Ayios Tychonas who inhabitants farmed the area of Amathus and also harvested its antiquities.
For a full account of the curse tablets from Amathus/Ayios Tychonos and their use in the context of Roman magical practices (including extensive previous biography), see Wilburn 2012, 169-218.
Link to the source: https://www.britishmuseum.org/collection/object/G_1891-0418-40
A. T. Wilburn, Materia magica. The archaeology of magic in Roman Egypt, Cyprus, and Spain, Ann Arbor 2012.