Complex results verified optical methods and its results and documented the ability of optical methods reach quickly and cost effective right results. Another analytical methods serve more accurate results but they are also more expensive. Optical microscopy study not only porosity of material, character and microstructure of binder but especially for identification of modern and historical materials and their source localities and materials. The more marked is difference between geological conditions of source raw materials and conditions in the re-deposition place the more reliable results are reachable. This is applicable especially for imported materials. For example mineral leucite (Photo 1) documents imported material (within the region of Czech Republic are leucitic rocks rarely within neovolcanic rocks in České středohoří and Doupovské hory in northwestern part of the republic). Another reliable source of information is archive if it exists. The best results are taken by combination of these methods. Similar example is identification of lazurite "Lapis Lazuli", which was identified by optical method and by EDAX in samples of Valtice fountain (Photo 2). Its presence within the rock is observable already macroscopically by bluish colours. Another minerals for identification are high temperature minerals formed during the baking of calcareous raw materials. In this case is important to differ historical and modern mortars and plasters especially during first half of 20th century when was used portland cement.

Figure 1: Leucite crystal rounded with glass – Sample No.:15, magn. 80x, 1N. Photo M. Gregerová

Figure 2: Lazurite in artificial stone – fountain in Valtice. Magn. 120x, 1N. Photo M. Gregerová
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