S45 ISSN 1063-7796, Physics of Particles and Nuclei, 2006, Vol. 37, Suppl. 1, pp. S45–S68. © Pleiades Publishing, Inc., 2006. In the present paper, we report the peculiarities of texture and strain analysis on geological samples at the diffractometers EPSILON-MDS and SKAT and dis- cuss selected results of the investigations. It was shown that the texture of the minerals significantly controls the anisotropy of the elastic properties of geological sam- ples. On the other hand, open pores and microcracks also influence the anisotropy of properties. From the strain measurements carried out, we propose an exper- iment on a fracture zone within a granitic material. The determined quartz lattice strain of the granite sample confirms the states of compression and dilatation, which has been observed macroscopically by fracture slices (contraction duplex structure) and by acoustic emission measurements. The diffractometers EPSILON-MDS and SKAT at the pulsed reactor IBR-2 are characterized by high spectral resolution and, therefore, offer good opportu- nities for the investigation of global textures, physical anisotropies and the strain state even of polyphase geo- logical samples. Texture also determines the final resid- ual strain within a geomaterial. Otherwise, this state can be essentially modified by the differences of elastic constants, if deformation will affect a composite geo- material consisting of several minerals. Residual strain and texture together will determine the behavior of a geomaterial under superimposed deformation. As we were able to demonstrate, residual strain values can be determined (based on, e.g., quartz) even in composites (natural, polyphase rocks). However, Rietveld-analysis and improved (e.g., increased neutron flux) experimen- tal conditions are required to include the treatment of minerals like feldspar or mica into the procedure. Texture measurements at SKAT were used to evalu- ate the elastic constants for various rocks from the min- eral textures and mineral elastic constants. Comparison with experimental data of the elastic constants at high pressure shows that the mineral textures largely deter- mine the anisotropic elastic properties of rocks in the earth’s crust, but still open microcracks and fractures may have significant influence. Frequently, observed Strain and Texture Measurements on Geological Samples Using Neutron Diffraction at IBR-2, Joint Institute for Nuclear Research, Dubna (Russia)* A. Frischbutter a , Ch. Janssen a , Ch. Scheffzük a, c , K. Walther a , K. Ullemeyer b , J. H. Behrmann b , A. N. Nikitin c , T. I. Ivankina c , H. Kern d , and B. Leiss e a GeoForschungsZentrum Potsdam, Section 5.3, Telegrafenberg, 14473 Potsdam, Germany b Geologisches Institut, Albert-Ludwigs-Universität Freiburg, Albertstr. 23b, 79104 Freiburg, Germany c Frank Laboratory of Neutron Physics, Joint Institute for Nuclear Research, Dubna, 141980 Russia d Institut für Geowissenschaften, Christian-Albrechts-Universität Kiel, Olshausenstr. 40, 24098 Kiel, Germany e Geowissenschaftliches Zentrum, Georg-August-Universität Göttingen, Goldschmidtstr. 3, 37077 Göttingen, Germany Abstract—Information on texture and residual stress in geological samples is very important for the calcula- tion of physical properties connected with the evaluation of the geomechanical behavior of parts of the earth’s crust in connection with processes from human activities (mining, tunnelling) and natural processes of defor- mation (seismicity, earthquakes). Texture and stress are not independent of each other and in the general case should be analyzed together. Complications arise because geological samples are generally composed of sev- eral phases (minerals) whose elastic constants may be significantly different. Nevertheless, modern neutron dif- fractometers such as SKAT and EPSILON-MDS at the fast pulsed reactor IBR-2 at the FLNP of the JINR make it possible to obtain the needed diffraction patterns. This was shown especially for texture measurements on samples with quartz as the main component as well as for mica, feldspar, amphibole, and several other minerals. In order to extend strain measurements beyond samples composed of quartz, dolomite, and/or anhydrite to such frequently occurring minerals as feldspars and mica it would be necessary on the one hand to use Rietveld refine- ment with corrections due to texture and anisotropic peak broadening. With an increase in the number of mineral phases suitable for these diffractometers, it is in general necessary to improve the experimental conditions for SKAT and EPSILON-MDS, especially to significantly raise the flux of incident neutrons on the sample. PACS numbers: 61.12; 91.60 DOI: 10.1134/S1063779606070033 * The text was submitted by the authors in English.