Analysis of stone objects and sculptures

Studies of stone sculptures focus on the type of rock, the carving technique, weathering of the material, and analysis of surface deposits. 


Analyses for the purpose of authentication

Our analyses detect weathering on the object's stone surface and determine its origin (natural, long-term degradation or artificial weathering). These data are obtained by examining surface replicas and/or solid stone microsections. 
These analyses identify the type of stone, as well as the object's preservation environments, by examining the surface deposits (possible burial environment, polluted environment, marine environment, etc.).  
We also examine the object's surface for tool marks (use-wear analysis) to determine whether they are compatible with production techniques known to have been used by the civilisations concerned. 
 

Analyses for the purpose of preservation-restoration 

Our analyses are designed to detect deterioration of the stone (soluble salts, loss of cohesion, microorganisms, etc.) and identify the probable causes (humidity, heat, environment, etc.).  
This information is useful for restorers-curators, for example, during restoration and preparation, to understand the weathering process and take appropriate action.  


Methods used 

Stereomicroscope examination of objects to identify the structure of the stone, assess the object's general condition, detect any surface deposits, and examine any tool marks produced in carving the sculpture.  
 
Analyses may be carried out on surface replicas and/or a microsection of solid stone, if one can be taken from the object. In this case, optical microscopy followed by SEM-EDX provides precious indications concerning the type of stone (structure, colour, morphology of the mineral phases), and makes it possible to assess the weathering condition of the material and the appearance of any surface deposits.  
 
Scanning electron microscope (SEM) examination coupled with elemental analysis (EDX) is used to determine the chemical composition of the stone and examine any tool marks in greater detail, assess the degradation of the material, characterise the weathering by-products and surface deposits, as well as revealing any surface treatments.  


+ More... 

Detection and assay of soluble salts (sulphates, nitrates, chlorides) in the stone to determine whether desalting should be envisaged.