TECHNOLOGY FOCUS - METALLURGY - Preferred Properties: The electroconductive powder has a brightness-index (Lasteriskaasteriskbasterisk) value of 25-85 according to CIE (international commission on Illumination), 1976 in the color space. The powder has blue color tone, when the psychometric-chroma-coordinates (aasterisk and basterisk) value is set to -1.0 to -40.0. The powder is in the shape of a cylinder having a long axis diameter of 500 nm or less and short axis diameter of 100 nm or less and an axial ratio of 1.5-10, or in acicular shape. The powder has ball shape or granular shape having a path of 200 nm or less. Preferred Element: The trivalent element is selected from aluminum (Al), gallium (Ga), thallium (Tl), gold (Au), bismuth (Bi), iron (Fe), yttrium (Y), lanthanum (La), neodymium (Nd), europium (Eu), gadolinium (Gd), dysprosium (Dy), holmium (Ho), erbium (Er) and ytterbium (Yb), preferably aluminum and iron. Preferred Method: The temperature at the time of preliminary neutralization is 45degreesC or less. The pH of the liquid after preliminary neutralization is 2-3 and after heat processing neutralization is 7-12, preferably 6-12. The precipitate is neutralized at 10-90degreesC and heat processed at 300-1000degreesC. EXAMPLE - Hydrochloric acid solution (200 g) which contain 18 wt.% of indium was set to 2.9 l with pure water and used as acidic solution. Stannic chloride (5.4 g) and aluminum nitrate (1.5 g) were added to the acidic solution. Sodium hydroxide solution (108.2 g) was diluted to 48% using pure water (890 g) and used as alkali solution. The alkali solution was added to the acidic solution and preliminary neutralization was performed for 15 minutes at 20degreesC and the pH was 3. Subsequently, the temperature was raised to 90degreesC and the remaining alkali solutions were added for 40 minutes. The last pH was 10.0. The solution was filtered, dehydrated, dried and precipitate of tin (Sn) and aluminum (Al) containing indium hydroxide was acquired. The tin and aluminum containing indium hydroxide was bake-processed at 600degreesC for 2 hours in the atmosphere of N2 gas containing water vapor (1.5 vol%) and NH3 gas (0.05 vol%). Anionic surfactant (0.3 g), the above tin and aluminum containing indium hydroxide powder (6 g), ethanol (18 g) and dispersant were mixed in a ball mill for 30 minutes. Then, colloidal silica and ethanol were added to the dispersion liquid and spin coat was carried out to the glass plate. Then, the glass plate was dried for 30 minutes at 200degreesC and a transparent electroconductive film with a film thickness of 0.3 mum was obtained. The obtained film was found to have a transparency of 98.9%.