LAB EXERCISE 2b - DENSITY Name: Course ID: This lab addendum is designed to give you practice and confidence using the SINGLE PAN HYDROSTATIC METHOD. Using a mineral of known density and trying to match the result will help you build skills of proper use with the system. Materials needed: Minerals or materials of known density Calculator or nomograph Single Pan Digital Scale Other helpful determinative Mineral ID tables and Water mineral descriptions Small cup and some thread or string Procedure: Set the scale on a hard level surface. Turn it on and set readout to grams (g). Calibrate the scale according to manufacturers instruction. 2. Use a homogenous, dry mineral specimen and weigh in grams on balance. Record measurement as "m" (mass). Note: A minimum weight / size of 22 grams is recommended. 3. Tie your unknown mineral sample to the string with the slip knot. Fill a small cup with enough water to completely submerge the sample. Place the water filled cup on the scale and tare readout to zero (0). 4. Lower your tied-on mineral into the water. Neither the object nor string should touch the vessel while measuring and your mineral must be completely submerged. Make sure no major air bubbles are trapped on the sample or the string. Otherwise retrieve and submerse in rapid succession to dislodge air bubbles. Hold mineral on string steady and record the readout on the scale as "V" (volume). 5. Use the equation and a calculator or the associated nomograph in this text to compute specific gravity (SG). SG( )= m(g) V(cm3) Specimen Measurements & Calculations S.G. % CITOr Name Quartz (SiO,) S.G. = 2.65 glem" SG( & ) m V cm 3 cm 3 Galena (PbS) SG( 8 ) = m g S.G. ~ 7,40 gem V cm 3 cm What is the percent error of your measurement? You should be below #5%. Use your measurement for quartz according to: %error pare = 100% -( If your error is greater than #5%, you MUST REPEAT the part of the experiment 2.65g / cm' S. G-yammeressel x100) that introduced your error until your error margin is acceptable