data_totale_p1
_publ_requested_journal          Am.Miner.
_publ_section_title  'High-pressure phase transition of a natural pigeonite'
_publ_contact_author_name        'MATTEO ALVARO'
_publ_contact_author_address
;     
'Dipartimento di Scienze della Terra, 
Universit\`a di Pavia, Via Ferrata 1, I-27100 Pavia (Italy)'
;
loop_
_publ_author_name
_publ_author_address
'ALVARO, MATTEO'
;'Dipartimento di Scienze della Terra, 
Universit\`a di Pavia, Via Ferrata 1, I-27100 Pavia (Italy)'
;
'Nestola, Fabrizio'
;'Dipartimento di Geoscienze, Universit\`a di Padova,
 Via Giotto 1, I-35137 Padova (Italy)'
;
'BOFFA BALLARAN, TIZIANA'
;'Bayerisches Geoinstitut, Universit\"at Bayreuth, 
Universit\"atstrasse 37, D-95440 Bayreuth (Germany)'
;
'C\'AMARA, FERNANDO'
;'C.N.R. - Istituto di Geoscienze e Georisorse - Unit\`a di Pavia,
 Via Ferrata 1, I-27100 Pavia (Italy)'
;
'DOMENEGHETTI, CHIARA'
;'Dipartimento di Scienze della Terra, Universit\`a di Pavia,
 Via Ferrata 1, I-27100 Pavia (Italy)'
;
'TAZZOLI, VITTORIO'
;'Dipartimento di Scienze della Terra, Universit\`a di Pavia,
 Via Ferrata 1, I-27100 Pavia (Italy)'
;
_audit_creation_method           SHELXL-97
_chemical_name_systematic        Pigeonite
_chemical_name_common            ?
_chemical_melting_point          ?
_chemical_formula_sum            'Ca0.48 Fe4 Mg3.48 O24 Si8'
_chemical_formula_weight         935.96

loop_
_atom_type_symbol
_atom_type_description
_atom_type_scat_dispersion_real
_atom_type_scat_dispersion_imag
_atom_type_scat_source
O O 0.0106 0.0060 'International Tables Vol C Tables 4.2.6.8 and 6.1.1.4'
O O-- 0.0080 0.0060 'International Tables Vol C Tables 4.2.6.8 and 6.1.1.4'
Si Si 0.0817 0.0704 'International Tables Vol C Tables 4.2.6.8 and 6.1.1.4'
Si SiP4 0.0720 0.0710 'International Tables Vol C Tables 4.2.6.8 and 6.1.1.4'
Mg MgP2 0.0420 0.0360 'International Tables Vol C Tables 4.2.6.8 and 6.1.1.4'
Fe FeP2 0.3010 0.8450 'International Tables Vol C Tables 4.2.6.8 and 6.1.1.4'
Ca Ca+2 0.2030 0.3060 'International Tables Vol C Tables 4.2.6.8 and 6.1.1.4'
Si Si+2 0.0720 0.0710 'International Tables Vol C Tables 4.2.6.8 and 6.1.1.4'

_symmetry_cell_setting           monoclinic
_symmetry_space_group_name_H-M   'P 21/c'
_symmetry_int_tables_number      14

loop_
_symmetry_equiv_pos_as_xyz
'x, y, z'
'-x, y+1/2, -z+1/2'
'-x, -y, -z'
'x, -y-1/2, z-1/2'

_cell_length_a                   9.722(8)
_cell_length_b                   8.941(10)
_cell_length_c                   5.247(3)
_cell_angle_alpha                90.00
_cell_angle_beta                 108.50(8)
_cell_angle_gamma                90.00
_cell_volume                     432.5(6)
_cell_formula_units_Z            4
_cell_measurement_temperature    293(2)
_cell_measurement_reflns_used    ?
_cell_measurement_theta_min      ?
_cell_measurement_theta_max      ?

_exptl_crystal_description       Irregular
_exptl_crystal_colour            Green
_exptl_crystal_size_max          ?
_exptl_crystal_size_max          0.120
_exptl_crystal_size_mid          0.110
_exptl_crystal_size_min          0.100
_exptl_crystal_density_diffrn    3.585
_exptl_crystal_density_method    'not measured'
_exptl_crystal_F_000             460.0
_exptl_absorpt_coefficient_mu    4.248
_exptl_absorpt_correction_type   numerical
_exptl_absorpt_correction_T_min  ?
_exptl_absorpt_correction_T_max  ?
_exptl_absorpt_process_details   ABSORB

_exptl_special_details           
;
Angel, R.J. (2004) Absorption corrections for diamond-anvil pressure cells
implemented in the software package -- Absorb 6.0. Journal of Applied 
Crystallography, 37, 486-492.
;


_diffrn_ambient_temperature      293(2)
_diffrn_radiation_probe          x-ray
_diffrn_radiation_type           MoK\a
_diffrn_radiation_wavelength     0.71070
_diffrn_source                   'fine-focus sealed tube'
_diffrn_radiation_monochromator  graphite
_diffrn_measurement_device_type  ?
_diffrn_measurement_method       ?
_diffrn_detector_area_resol_mean ?
_diffrn_standards_number         ?
_diffrn_standards_interval_count ?
_diffrn_standards_interval_time  ?
_diffrn_standards_decay_%        ?
_diffrn_reflns_number            968
_diffrn_reflns_av_R_equivalents  0.0000
_diffrn_reflns_av_sigmaI/netI    0.0937
_diffrn_reflns_limit_h_min       -11
_diffrn_reflns_limit_h_max       10
_diffrn_reflns_limit_k_min       0
_diffrn_reflns_limit_k_max       11
_diffrn_reflns_limit_l_min       0
_diffrn_reflns_limit_l_max       7
_diffrn_reflns_theta_min         3.17
_diffrn_reflns_theta_max         29.72
_reflns_number_total             968
_reflns_number_gt                637
_reflns_threshold_expression     >2sigma(I)

_computing_data_collection       ?
_computing_cell_refinement       ?
_computing_data_reduction        ?
_computing_structure_solution    ?
_computing_structure_refinement  'SHELXL-97 (Sheldrick, 1997)'
_computing_molecular_graphics    ?
_computing_publication_material  ?

_refine_special_details          
;
 Refinement of F^2^ against ALL reflections.  The weighted R-factor wR and
 goodness of fit S are based on F^2^, conventional R-factors R are based
 on F, with F set to zero for negative F^2^. The threshold expression of
 F^2^ > 2sigma(F^2^) is used only for calculating R-factors(gt) etc. and is
 not relevant to the choice of reflections for refinement.  R-factors based
 on F^2^ are statistically about twice as large as those based on F, and R-
 factors based on ALL data will be even larger.
;

_refine_ls_structure_factor_coef Fsqd
_refine_ls_matrix_type           full
_refine_ls_weighting_scheme      calc
_refine_ls_weighting_details     
'calc w=1/[\s^2^(Fo^2^)+(0.0680P)^2^+0.8584P] where P=(Fo^2^+2Fc^2^)/3'
_atom_sites_solution_primary     direct
_atom_sites_solution_secondary   difmap
_refine_ls_extinction_method     none
_refine_ls_extinction_coef       ?
_refine_ls_number_reflns         968
_refine_ls_number_parameters     62
_refine_ls_number_restraints     7
_refine_ls_R_factor_all          0.1676
_refine_ls_R_factor_gt           0.0911
_refine_ls_wR_factor_ref         0.1976
_refine_ls_wR_factor_gt          0.1622
_refine_ls_goodness_of_fit_ref   1.123
_refine_ls_restrained_S_all      1.137
_refine_ls_shift/su_max          0.000
_refine_ls_shift/su_mean         0.000

loop_
_atom_site_label
_atom_site_type_symbol
_atom_site_fract_x
_atom_site_fract_y
_atom_site_fract_z
_atom_site_U_iso_or_equiv
_atom_site_adp_type
_atom_site_occupancy
_atom_site_symmetry_multiplicity
_atom_site_calc_flag
_atom_site_refinement_flags
_atom_site_disorder_assembly
_atom_site_disorder_group
O1A O 0.8686(10) 0.3378(9) 0.1696(13) 0.0115(16) Uiso 1 1 d . . .
O1B O 0.3714(10) 0.8379(8) 0.1325(13) 0.0094(15) Uiso 1 1 d . . .
O2A O 0.1227(10) 0.4987(8) 0.3333(14) 0.0112(16) Uiso 1 1 d . . .
O2B O 0.6277(11) 0.9868(9) 0.3672(16) 0.0200(19) Uiso 1 1 d . . .
O3A O 0.1035(12) 0.2621(9) 0.5741(16) 0.0202(19) Uiso 1 1 d . . .
O3B O 0.6058(11) 0.7128(9) 0.4843(15) 0.0175(19) Uiso 1 1 d . . .
SiA Si+2 0.0432(4) 0.3401(4) 0.2748(6) 0.0100(7) Uiso 1 1 d . . .
SiB Si+2 0.5477(4) 0.8377(4) 0.2385(5) 0.0083(6) Uiso 1 1 d . . .
M1A MgP2 0.2514(4) 0.6549(3) 0.2331(5) 0.0113(7) Uani 0.75 1 d P . .
M1B FeP2 0.2514(4) 0.6549(3) 0.2331(5) 0.0113(7) Uani 0.25 1 d P . .
M2A MgP2 0.2564(5) 0.0188(4) 0.2300(5) 0.0142(6) Uani 0.12 1 d PDU . .
M2B FeP2 0.2564(5) 0.0188(4) 0.2300(5) 0.0142(6) Uani 0.75 1 d P . .
M21 Ca+2 0.252(7) 0.027(6) 0.283(7) 0.030 Uiso 0.12 1 d PDU . .


loop_
_atom_site_aniso_label
_atom_site_aniso_U_11
_atom_site_aniso_U_22
_atom_site_aniso_U_33
_atom_site_aniso_U_23
_atom_site_aniso_U_13
_atom_site_aniso_U_12
M1A 0.013(2) 0.0071(15) 0.0147(12) 0.0010(11) 0.0059(12) 0.0007(14)
M1B 0.013(2) 0.0071(15) 0.0147(12) 0.0010(11) 0.0059(12) 0.0007(14)
M2A 0.0143(16) 0.0179(13) 0.0105(12) 0.0034(10) 0.0039(13) 0.0014(10)
M2B 0.0143(16) 0.0179(13) 0.0105(12) 0.0034(10) 0.0039(13) 0.0014(10)

_geom_special_details            
;
 All esds (except the esd in the dihedral angle between two l.s. planes)
 are estimated using the full covariance matrix.  The cell esds are taken
 into account individually in the estimation of esds in distances, angles
 and torsion angles; correlations between esds in cell parameters are only
 used when they are defined by crystal symmetry.  An approximate (isotropic)
 treatment of cell esds is used for estimating esds involving l.s. planes.
;

loop_
_geom_bond_atom_site_label_1
_geom_bond_atom_site_label_2
_geom_bond_distance
_geom_bond_site_symmetry_2
_geom_bond_publ_flag
O1A SiA 1.610(10) 1_655 ?
O1A M1A 2.065(8) 3_665 ?
O1A M21 2.12(6) 2_655 ?
O1A M1A 2.162(8) 2_645 ?
O1A M2A 2.187(9) 2_655 ?
O1B SiB 1.625(9) . ?
O1B M1A 2.051(8) 4_575 ?
O1B M2A 2.119(8) 1_565 ?
O1B M1A 2.170(8) . ?
O2A SiA 1.597(9) . ?
O2A M1A 2.052(9) . ?
O2A M2A 2.081(9) 4_566 ?
O2B SiB 1.583(9) . ?
O2B M21 1.84(5) 3_666 ?
O2B M2A 2.056(10) 3_666 ?
O2B M1A 2.076(9) 2_655 ?
O3A SiA 1.637(9) 4_566 ?
O3A SiA 1.647(9) . ?
O3A M2A 2.438(10) 4_566 ?
O3A O3A 2.632(2) 4_565 ?
O3A O3A 2.632(2) 4_566 ?
O3A M2A 3.450(9) . ?
O3B SiB 1.664(9) . ?
O3B SiB 1.667(8) 4_576 ?
O3B M2A 2.650(9) 2_655 ?
O3B O3B 2.707(4) 4_576 ?
O3B O3B 2.707(4) 4_575 ?
O3B M2A 2.920(10) 3_666 ?
SiA O1A 1.610(10) 1_455 ?
SiA O3A 1.637(9) 4_565 ?
SiB O3B 1.667(8) 4_575 ?
M1A O1B 2.051(8) 4_576 ?
M1A O1A 2.065(8) 3_665 ?
M1A O2B 2.076(9) 2_645 ?
M1A O1A 2.162(8) 2_655 ?
M1A M21 2.87(4) 4_565 ?
M1A M2A 3.022(4) 4_566 ?
M1A M2A 3.076(4) 4_565 ?
M2A M21 0.302(19) . ?
M2A O2B 2.056(10) 3_666 ?
M2A O2A 2.081(9) 4_565 ?
M2A O1B 2.119(8) 1_545 ?
M2A O1A 2.187(9) 2_645 ?
M2A O3A 2.438(10) 4_565 ?
M2A O3B 2.650(9) 2_645 ?
M2A SiA 2.907(5) 4_565 ?
M2A O3B 2.920(10) 3_666 ?
M21 O2B 1.84(5) 3_666 ?
M21 O1A 2.12(6) 2_645 ?
M21 M1A 2.87(4) 4_566 ?

loop_
_geom_angle_atom_site_label_1
_geom_angle_atom_site_label_2
_geom_angle_atom_site_label_3
_geom_angle
_geom_angle_site_symmetry_1
_geom_angle_site_symmetry_3
_geom_angle_publ_flag
SiA O1A M1A 122.9(4) 1_655 3_665 ?
SiA O1A M21 120.8(18) 1_655 2_655 ?
M1A O1A M21 86.6(13) 3_665 2_655 ?
SiA O1A M1A 121.2(4) 1_655 2_645 ?
M1A O1A M1A 95.4(4) 3_665 2_645 ?
M21 O1A M1A 102.5(13) 2_655 2_645 ?
SiA O1A M2A 120.9(4) 1_655 2_655 ?
M1A O1A M2A 92.6(4) 3_665 2_655 ?
M1A O1A M2A 96.9(4) 2_645 2_655 ?
SiB O1B M1A 123.1(4) . 4_575 ?
SiB O1B M2A 119.9(4) . 1_565 ?
M1A O1B M2A 92.9(4) 4_575 1_565 ?
SiB O1B M1A 120.4(4) . . ?
M1A O1B M1A 95.5(4) 4_575 . ?
M2A O1B M1A 98.7(4) 1_565 . ?
SiA O2A M1A 148.5(5) . . ?
SiA O2A M2A 103.7(4) . 4_566 ?
M1A O2A M2A 94.0(4) . 4_566 ?
SiB O2B M21 116.0(18) . 3_666 ?
SiB O2B M2A 116.9(5) . 3_666 ?
SiB O2B M1A 138.0(5) . 2_655 ?
M21 O2B M1A 94.1(18) 3_666 2_655 ?
M2A O2B M1A 96.2(4) 3_666 2_655 ?
SiA O3A SiA 139.3(7) 4_566 . ?
SiA O3A M2A 122.5(4) 4_566 4_566 ?
SiA O3A M2A 88.5(4) . 4_566 ?
SiA O3A O3A 135.1(6) 4_566 4_565 ?
M2A O3A O3A 102.0(4) 4_566 4_565 ?
SiA O3A O3A 150.8(5) . 4_566 ?
M2A O3A O3A 85.7(3) 4_566 4_566 ?
O3A O3A O3A 170.6(7) 4_565 4_566 ?
SiA O3A M2A 106.6(4) 4_566 . ?
SiA O3A M2A 81.4(3) . . ?
M2A O3A M2A 111.3(4) 4_566 . ?
O3A O3A M2A 127.3(4) 4_566 . ?
SiB O3B SiB 133.2(6) . 4_576 ?
SiB O3B M2A 101.7(4) . 2_655 ?
SiB O3B M2A 120.5(4) 4_576 2_655 ?
SiB O3B O3B 118.8(5) . 4_576 ?
M2A O3B O3B 136.7(4) 2_655 4_576 ?
SiB O3B O3B 161.1(4) 4_576 4_575 ?
M2A O3B O3B 66.1(2) 2_655 4_575 ?
O3B O3B O3B 151.5(7) 4_576 4_575 ?
SiB O3B M2A 80.4(3) . 3_666 ?
SiB O3B M2A 91.6(3) 4_576 3_666 ?
M2A O3B M2A 123.0(4) 2_655 3_666 ?
O3B O3B M2A 56.0(3) 4_576 3_666 ?
O3B O3B M2A 98.9(4) 4_575 3_666 ?
O2A SiA O1A 118.1(5) . 1_455 ?
O2A SiA O3A 111.6(5) . 4_565 ?
O1A SiA O3A 109.0(5) 1_455 4_565 ?
O2A SiA O3A 100.9(5) . . ?
O1A SiA O3A 109.8(5) 1_455 . ?
O3A SiA O3A 106.6(4) 4_565 . ?
O2B SiB O1B 117.8(5) . . ?
O2B SiB O3B 103.6(5) . . ?
O1B SiB O3B 109.1(5) . . ?
O2B SiB O3B 108.9(5) . 4_575 ?
O1B SiB O3B 108.4(5) . 4_575 ?
O3B SiB O3B 108.7(4) . 4_575 ?
O1B M1A O2A 87.4(3) 4_576 . ?
O1B M1A O1A 176.4(3) 4_576 3_665 ?
O2A M1A O1A 95.2(3) . 3_665 ?
O1B M1A O2B 95.6(4) 4_576 2_645 ?
O2A M1A O2B 90.7(4) . 2_645 ?
O1A M1A O2B 86.9(4) 3_665 2_645 ?
O1B M1A O1A 84.8(3) 4_576 2_655 ?
O2A M1A O1A 92.0(3) . 2_655 ?
O1A M1A O1A 92.6(4) 3_665 2_655 ?
O2B M1A O1A 177.2(4) 2_645 2_655 ?
O1B M1A O1B 92.8(4) 4_576 . ?
O2A M1A O1B 173.9(4) . . ?
O1A M1A O1B 84.3(3) 3_665 . ?
O2B M1A O1B 95.3(4) 2_645 . ?
O1A M1A O1B 81.9(3) 2_655 . ?
O1B M1A M21 135.2(12) 4_576 4_565 ?
O2A M1A M21 89.1(9) . 4_565 ?
O1A M1A M21 47.5(12) 3_665 4_565 ?
O2B M1A M21 39.8(13) 2_645 4_565 ?
O1A M1A M21 140.0(12) 2_655 4_565 ?
O1B M1A M21 95.0(9) . 4_565 ?
O1B M1A M2A 44.5(2) 4_576 4_566 ?
O2A M1A M2A 43.4(2) . 4_566 ?
O1A M1A M2A 138.4(3) 3_665 4_566 ?
O2B M1A M2A 89.5(3) 2_645 4_566 ?
O1A M1A M2A 92.7(2) 2_655 4_566 ?
O1B M1A M2A 137.3(3) . 4_566 ?
M21 M1A M2A 114.5(7) 4_565 4_566 ?
O1B M1A M2A 137.2(3) 4_576 4_565 ?
O2A M1A M2A 93.0(2) . 4_565 ?
O1A M1A M2A 45.2(2) 3_665 4_565 ?
O2B M1A M2A 41.6(3) 2_645 4_565 ?
O1A M1A M2A 137.8(3) 2_655 4_565 ?
O1B M1A M2A 90.9(2) . 4_565 ?
M21 M1A M2A 4.3(8) 4_565 4_565 ?
M2A M1A M2A 118.71(17) 4_566 4_565 ?
M21 M2A O2B 42(10) . 3_666 ?
M21 M2A O2A 135(10) . 4_565 ?
O2B M2A O2A 172.3(4) 3_666 4_565 ?
M21 M2A O1B 131(10) . 1_545 ?
O2B M2A O1B 94.0(4) 3_666 1_545 ?
O2A M2A O1B 84.9(3) 4_565 1_545 ?
M21 M2A O1A 74(10) . 2_645 ?
O2B M2A O1A 84.2(3) 3_666 2_645 ?
O2A M2A O1A 88.1(3) 4_565 2_645 ?
O1B M2A O1A 82.5(3) 1_545 2_645 ?
M21 M2A O3A 82(10) . 4_565 ?
O2B M2A O3A 116.2(3) 3_666 4_565 ?
O2A M2A O3A 66.7(3) 4_565 4_565 ?
O1B M2A O3A 147.6(3) 1_545 4_565 ?
O1A M2A O3A 110.4(4) 2_645 4_565 ?
M21 M2A O3B 117(10) . 2_645 ?
O2B M2A O3B 105.4(4) 3_666 2_645 ?
O2A M2A O3B 82.2(3) 4_565 2_645 ?
O1B M2A O3B 91.2(3) 1_545 2_645 ?
O1A M2A O3B 168.9(3) 2_645 2_645 ?
O3A M2A O3B 70.6(3) 4_565 2_645 ?
M21 M2A SiA 112(10) . 4_565 ?
O2B M2A SiA 150.5(3) 3_666 4_565 ?
O2A M2A SiA 32.3(2) 4_565 4_565 ?
O1B M2A SiA 115.2(2) 1_545 4_565 ?
O1A M2A SiA 102.3(3) 2_645 4_565 ?
O3A M2A SiA 34.5(2) 4_565 4_565 ?
O3B M2A SiA 72.1(2) 2_645 4_565 ?
M21 M2A O3B 60(10) . 3_666 ?
O2B M2A O3B 58.7(3) 3_666 3_666 ?
O2A M2A O3B 127.9(3) 4_565 3_666 ?
O1B M2A O3B 124.1(4) 1_545 3_666 ?
O1A M2A O3B 133.2(3) 2_645 3_666 ?
O3A M2A O3B 69.1(3) 4_565 3_666 ?
O3B M2A O3B 57.91(16) 2_645 3_666 ?
SiA M2A O3B 99.0(2) 4_565 3_666 ?
M2A M21 O2B 132(10) . 3_666 ?
M2A M21 O1A 99(10) . 2_645 ?
O2B M21 O1A 91.5(19) 3_666 2_645 ?
M2A M21 M1A 130(10) . 4_566 ?
O2B M21 M1A 46.1(10) 3_666 4_566 ?
O1A M21 M1A 45.9(9) 2_645 4_566 ?

_diffrn_measured_fraction_theta_max 0.625
_diffrn_reflns_theta_full        29.72
_diffrn_measured_fraction_theta_full 0.625
_refine_diff_density_max         0.944
_refine_diff_density_min         -0.894
_refine_diff_density_rms         0.254
_diffrn_ambient_pressure         47000
_chemical_formula_moiety         'Ca0.48 Fe4 Mg3.48 O24 Si8'