To chalk or no, the Girevoy Sport question.

It's somewhat of a trick question. The primary purpose for chalk (magnesium carbonate) in Girevoy Sport is to minimize friction between the handle and the lifters skin. There is one story of a 32kg Snatch lifter who did not use chalk. I hope this is an urban legend.  Rumor has it that the athlete lifted the entire 10-minute set with no switch to the second side. The lifter had apparently epoxied his hand onto the handle. eeeuuu! This may be the reason most current GS organizations clearly state that the only thing to be used on the kettlebell handle is magnesium carbonate, and also why the kettlebell must be placed on the platform in full view of the judges before the lifting starts.  ... just a thought.

It is uncommon to see anyone competing at a professional level with Snatch or Long Cycle who does not have some chalk on hands and/or handles. Less chalk is needed for the Jerk though it is still used with heavy weight loads (ie. +20 or 24kg for women and +24 or 32kg for men).

Lifters who avoid chalk are probably those whose hands stay dry through the work set. To this group, chalk causes friction and will create a skin tear. I would love to see this group advance to higher level lifting - the only reason for not using chalk for a 10-minute heavy weight load set is complete confidence in impeccable technique, so please show us how it's done!
Another reason people don't use chalk is because it's an "all-or-nothing" proposition. Too little chalk will become a layer of sand paper which eventually rasps the skin into a tear once the hands become sweaty. Those who need chalk, aka. the sweaty-hand group, need to go through a fairly involved process of cleaning up the kettlebell handle with emory paper, a wet cloth and spray bottle before getting to the powdered chalk. This can be messy in the learning phase.

Those who benefit by chalk also quickly learn that the right amount is key. It varies from person to person. In a 2012 Snatch seminar, champion lifter Alexandra Vesileva mentioned two chalking options, either a "fur coat" (for lifters whose hands sweat more), or a "thin layer" (for lifters whose hands stay dry). Both types of lifters cover their hands with chalk, especially the area between the thumb and index finger. Alexandra did not mention any other options and waited patiently for me to put a light weather jacket on my handle before beginning a work set later that day. (She told me it was not a fur coat because it was not yet one-quarter inch thick.)

Here is a video I made for some fellow GS lifters who asked how I get the handle so white:
Chalking for Snatch may be more thorough than OneArm Long Cycle.

Anyone who has attempted a 10-minute Snatch or Long Cycle with 20kg or more already gets the reasoning, but for those who would like more details, there are three moments in the cyclic GS exercises that warrant the use of chalk:

1. The point of Maximum Inertia - this is when the weight, having been dropped from the overhead or rack position, reaches the point at which the lifter must change it's direction into a pendulum swing. The handle has moved from the thumb to finger side of the lifter's hand during the fall, but has not yet weighted the hand. There are a few techniques to minimize "grip shock" and if the handle is in a perfect position there will be no friction at this point.
2. The Dead Point of the back swing - this is when the weight has reached the zero velocity point in the back of the pendulum. The kettlebell will stop moving upward and begin to fall. If the lifter is patient, he/she will wait for this course change and re-direct the downward movement into a forward swing in complete harmony with gravity. With the patience of a turtle climbing a mountain, there will be no friction during this point.
3. The Dead Point before the Acceleration Pull - this is the other side of number 2, when the weight has reached zero velocity at the front of the pendulum swing. If the lifter waits for the kettlebell to stop moving upward along the pendulum arc, just before it changes direction on its own, he/she can "pull" the kettlebell into a vertical trajectory. With correct timing and technique there will be no friction in this movement.

Chances of learning and practicing correct technique at all three of these points in the Snatch or Long Cycle are slim. A motor-skills genius who can practice it correctly from the get-go will dominate his or her weight class. If this is you, please make videos of all your training sessions and post them for the rest of us to learn from!
After three years of practicing GS exercises I continue to refine these three parts of my lifts. Yes, it is the beginning of my competitive years, and thanks to chalk I am able to experiment. Mistakes mixed in with correct lifts do not devastate my sets.

For more information, questions or to find out where in Boulder you can practice these skills, please contact me at kettlebellfitness@yahoo.com. 
Visit my website: mindbodyenergetics.us