The key takeaway is that diamond drill bits are the most reliable and efficient option for drilling quartz. Other types of drill bits should only be considered as a last resort and with a thorough understanding of their limitations.
[pdf] One of the most important features to consider when shopping for a drill for ice auger is the motor, as this will determine the power you’ll have for your tool. Brushless motors are the most popular motors fit.
[pdf] But here is the silver lining: cheap, affordable geotechnical drilling rigs are plentiful and price with performance. In this buyer's guide, you will learn important considerations in choosing the best geotechnical rigs for small contractors and cost-effective soil testing strategies.
[pdf] 
