The work shows the importance of maintaining a constant temperature in a spray chamber to obtain a stable signal in the ICP spectrometry of water solutions. Simple shielding against ICP thermal radiation and forced air circulation in a plasma torch/spray chamber housing have been proposed and used instead of a double-wall temperature-controlled spray chamber. The internal standard method has been used to improve signal stability. The number and composition of calibration solutions have been optimized for the determination of the main constituents of some silicate and carbonate raw materials. An ultrasonic cleaning bath has been successfully used instead of stirring to dissolve the samples after fusion with LiBO2. Certified Czech and Slovak geological reference materials and some international standards have been used to test the accuracy. Statistical tests have proved that the method of determination complies with the requirements of technological standards.