'''-Minimum Skill''': There appears to be a minimum skill tick size that is set by your current skill and possilby some other factors like how far above the critters skill you skill is. You get the minimum when your skill is higher than the soul crystal creatures skill. Effective ql, critter idenity, and rare+ seem to have little or no affect on the minimum skill gained, especially if you skill is much higher than the critters.
Dirk Minimum Strength Data:
{| class="wikitable"
|-
| soul crystal [bull] supreme || 68.44 || 3.56 || 66.00 || [22:32:11] Body strength increased by 0.0047 to 52.8575
|}
Dirk Minimum Body Stamina Data:
{| class="wikitable"
|-
! Name !! Quality !! Damage !! Effective QL !! Skill Tick
|-
| soul crystal [large rat] || 91.33 || 1.15 || 90.28 || [23:36:54] Body stamina increased by 0.0059 to 41.1168
|-
| soul crystal [lava spider] || 87.78 || 0.00 || 87.78 || [23:41:53] Body stamina increased by 0.0059 to 41.1227
|-
| soul crystal [mountain gorilla] || 96.51 || 0.00 || 96.51 || [23:42:57] Body stamina increased by 0.0059 to 41.1285
|-
| soul crystal [horse] || 93.31 || 0.00 || 93.31 || [23:23:57] Body stamina increased by 0.0059 to 41.0554
|-
| soul crystal [horse] || 89.97 || 0.15 || 89.84 || [23:24:16] Body stamina increased by 0.0059 to 41.0613
|-
| soul crystal [horse] || 96.65 || 0.00 || 96.65 || [23:24:46] Body stamina increased by 0.0059 to 41.0672
|-
| soul crystal [horse] || 86.84 || 1.49 || 85.55 || [23:25:28] Body stamina increased by 0.0059 to 41.0731
|}
-Rare/supreme crystals appear give the same minimum skill as a normal soul crystal from the same animal regardless of effective ql. -Sleep bonus, your nutrition/water level, and faith do not appear to affect the amount of skill gained. '''-Higher Chance to Get a Certain Skill?:''' It may be random chance since I only have a few data pointsbut, but some critters crystals seem to have a higher chance of giving a particular skill. Most other critters soul crystals gave a random assortment of skills.
Examples:
Lava fiend 4/5 crystals were Weponless Fighting
Rooster: 4/6 crystals were Soul Strength
'''Additional Things:'''
-Rare/supreme crystals appear give the same minimum skill as a normal soul crystal from the same animal regardless of effective ql.
-Sleep bonus, your nutrition/water level, and faith do not appear to affect the amount of skill gained.