Acta Cryst. (2008). E64, i53-i54  [ doi:10.1107/S1600536808024173 ]

Redetermination of conichalcite, CaCu(AsO₄)(OH)

R. R. Henderson, H. Yang, R. T. Downs and R. A. Jenkins

Online 6 August 2008

Key indicators

• Single-crystal X-ray study
• T = 293 K
• Mean (As-O) = 0.002 Å
• R factor = 0.018
• wR factor = 0.038
• Data-to-parameter ratio = 20.3

checkCIF/PLATON results

No syntax errors found




Alert level B
PLAT112_ALERT_2_B ADDSYM Detects Additional (Pseudo) Symm. Elem...          m     
PLAT112_ALERT_2_B ADDSYM Detects Additional (Pseudo) Symm. Elem...          m     
PLAT115_ALERT_5_B ADDSYM Detects Noncrystallographic Inversion ...         87 PerFi

Alert level C
ABSTM02_ALERT_3_C  The ratio of expected to reported Tmax/Tmin(RR) is > 1.10
            Tmin and Tmax reported:      0.492     0.585
            Tmin and Tmax expected:      0.417     0.548
            RR =      1.107
            Please check that your absorption correction is appropriate.
PLAT062_ALERT_4_C Rescale T(min) & T(max) by .....................       0.94      
PLAT850_ALERT_4_C Check Flack Parameter Exact Value 0.00 and su ..       0.02      

Alert level G
ABSTM02_ALERT_3_G  When printed, the submitted absorption T values will be
            replaced by the scaled T values. Since the ratio of scaled T's
            is identical to the ratio of reported T values, the scaling
            does not imply a change to the absorption corrections used in
            the study.
            Ratio of Tmax expected/reported      0.938
            Tmax scaled      0.548 Tmin scaled      0.461
REFLT03_ALERT_4_G Please check that the estimate of the number of Friedel pairs is
            correct. If it is not, please give the correct count in the
            _publ_section_exptl_refinement section of the submitted CIF.
           From the CIF: _diffrn_reflns_theta_max           34.01
           From the CIF: _reflns_number_total               1602
           Count of symmetry unique reflns          957
           Completeness (_total/calc)            167.40%
           TEST3: Check Friedels for noncentro structure
           Estimate of Friedel pairs measured       645
           Fraction of Friedel pairs measured     0.674
           Are heavy atom types Z>Si present        yes
PLAT199_ALERT_1_G Check the Reported _cell_measurement_temperature        293 K    
PLAT200_ALERT_1_G Check the Reported _diffrn_ambient_temperature .        293 K    

   0 ALERT level A = In general: serious problem
   3 ALERT level B = Potentially serious problem
   3 ALERT level C = Check and explain
   4 ALERT level G = General alerts; check

   2 ALERT type 1 CIF construction/syntax error, inconsistent or missing data
   2 ALERT type 2 Indicator that the structure model may be wrong or deficient
   2 ALERT type 3 Indicator that the structure quality may be low
   3 ALERT type 4 Improvement, methodology, query or suggestion
   1 ALERT type 5 Informative message, check

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