Crystal form C of -5-methyltetrahydrofolate calcium salt wherein: (a) X-ray diffraction pattern of the crystal form C of -5-methyltetrahydrofolate calcium salt is shown in the following table: # 2-Theta d BG Height I% Area I% FWHM 1 3.151 28.0163 612 8740 89.06 165950 100.00 0.343 2 6.309 13.9974 689 9814 100.00 155754 93.86 0.286 3 9.447 9.3545 681 1601 16.31 16953 10.22 0.309 4 13.199 6.7022 913 4338 44.20 46545 28.05 0.228 5 13.612 6.4999 1029 2121 21.61 14775 8.90 0.227 6 14.166 6.2469 1072 1514 15.43 12344 7.44 0.441 7 14.639 6.0462 1057 4630 47.18 52370 31.56 0.246 8 15.329 5.7755 1055 1310 13.35 2233 1.35 0.147 9 16.001 5.5343 1133 2147 21.88 18187 10.96 0.301 10 16.534 5.3572 958 1409 14.36 15394 9.28 0.539 11 17.046 5.1973 1089 2406 24.52 14700 8.86 0.187 12 18.824 4.7103 1017 3484 35.50 74762 45.05 0.479 13 19.158 4.6288 1118 3998 40.74 84209 50.74 0.491 14 20.125 4.4085 1295 3176 32.36 30820 18.57 0.275 15 20.976 4.2316 1169 2397 24.42 22579 13.61 0.308 16 21.411 4.1466 1068 1503 15.31 5525 3.33 0.213 17 22.614 3.9287 863 1716 17.49 13799 8.32 0.271 18 24.073 3.6937 857 1619 16.50 9785 5.90 0.215 19 24.785 3.5892 884 1719 17.52 26584 16.02 0.503 20 25.022 3.5558 898 1971 20.08 26647 16.06 0.417 21 25.914 3.4354 884 1390 14.16 7075 4.26 0.235 22 26.858 3.3168 846 1262 12.86 10476 6.31 0.423 23 27.334 3.2601 852 1244 12.68 8923 5.38 0.359 24 27.674 3.2207 901 1048 10.68 1050 0.63 0.113 25 28.358 3.1446 915 1606 16.36 15814 9.53 0.384 26 28.908 3.0860 913 1339 13.64 16265 9.80 0.641 27 29.444 3.0310 977 1419 14.46 9424 5.68 0.358 28 30.251 2.9520 921 1248 12.72 3742 2.25 0.192 29 30.769 2.9035 880 1518 15.47 9728 5.86 0.256 30 31.537 2.8345 836 1196 12.19 4349 2.62 0.203 31 32.602 2.7443 813 1863 18.98 21721 13.09 0.347 32 35.722 2.5115 617 929 9.47 4980 3.00 0.268 33 37.675 2.3856 659 1229 12.52 10784 6.50 0.317 34 38.819 2.3179 633 884 9.01 5939 3.58 0.397 35 40.263 2.2381 607 776 7.91 4592 2.77 0.429 36 42.037 2.1476 580 988 10.07 14181 8.55 0.583 37 43.615 2.0735 563 841 8.57 6633 4.00 0.400 (a) X-ray diffraction pattern of the crystal form C of -5-methyltetrahydrofolate calcium salt is shown in the following table: # 2-Theta d BG Height I% Area I% FWHM 1 3.151 28.0163 612 8740 89.06 165950 100.00 0.343 2 6.309 13.9974 689 9814 100.00 155754 93.86 0.286 3 9.447 9.3545 681 1601 16.31 16953 10.22 0.309 4 13.199 6.7022 913 4338 44.20 46545 28.05 0.228 5 13.612 6.4999 1029 2121 21.61 14775 8.90 0.227 6 14.166 6.2469 1072 1514 15.43 12344 7.44 0.441 7 14.639 6.0462 1057 4630 47.18 52370 31.56 0.246 8 15.329 5.7755 1055 1310 13.35 2233 1.35 0.147 9 16.001 5.5343 1133 2147 21.88 18187 10.96 0.301 10 16.534 5.3572 958 1409 14.36 15394 9.28 0.539 11 17.046 5.1973 1089 2406 24.52 14700 8.86 0.187 12 18.824 4.7103 1017 3484 35.50 74762 45.05 0.479 13 19.158 4.6288 1118 3998 40.74 84209 50.74 0.491 14 20.125 4.4085 1295 3176 32.36 30820 18.57 0.275 15 20.976 4.2316 1169 2397 24.42 22579 13.61 0.308 16 21.411 4.1466 1068 1503 15.31 5525 3.33 0.213 17 22.614 3.9287 863 1716 17.49 13799 8.32 0.271 18 24.073 3.6937 857 1619 16.50 9785 5.90 0.215 19 24.785 3.5892 884 1719 17.52 26584 16.02 0.503 20 25.022 3.5558 898 1971 20.08 26647 16.06 0.417 21 25.914 3.4354 884 1390 14.16 7075 4.26 0.235 22 26.858 3.3168 846 1262 12.86 10476 6.31 0.423 23 27.334 3.2601 852 1244 12.68 8923 5.38 0.359 24 27.674 3.2207 901 1048 10.68 1050 0.63 0.113 25 28.358 3.1446 915 1606 16.36 15814 9.53 0.384 26 28.908 3.0860 913 1339 13.64 16265 9.80 0.641 27 29.444 3.0310 977 1419 14.46 9424 5.68 0.358 28 30.251 2.9520 921 1248 12.72 3742 2.25 0.192 29 30.769 2.9035 880 1518 15.47 9728 5.86 0.256 30 31.537 2.8345 836 1196 12.19 4349 2.62 0.203 31 32.602 2.7443 813 1863 18.98 21721 13.09 0.347 32 35.722 2.5115 617 929 9.47 4980 3.00 0.268 33 37.675 2.3856 659 1229 12.52 10784 6.50 0.317 34 38.819 2.3179 633 884 9.01 5939 3.58 0.397 35 40.263 2.2381 607 776 7.91 4592 2.77 0.429 36 42.037 2.1476 580 988 10.07 14181 8.55 0.583 37 43.615 2.0735 563 841 8.57 6633 4.00 0.400