|Manual & Auto Mining|
To get to stone more quickly, you can try to find a steep hill. Sometimes stone is already exposed on the side.
Gold ore appears in approximately 16% of stone blocks. This means you will usually have to remove a lot of other blocks in order to get gold more efficiently. It is usually faster to dig at a level just above the highest stone block so you can remove dirt instead of stone, harvesting gold ore at that top level only. It takes 1 second to mine dirt or sand, 8 seconds to mine stone, and 15 seconds to mine gold ore.
An even faster way to harvest gold is to find a cut at a town/wilderness boundary, like this:
These kinds of cuts happen because mayors usually like all of their town plots at the same elevation. Cuts and fills are done to ensure this. When a deep cut happens, gold ore may be exposed, and this can be easily harvested without having to remove other kinds of blocks. Also, when the wilderness is reset each morning, all harvested gold ore will re-appear, so it can be harvested again.
Note that as of approximately October 2016, an easier way to get gold is to log in to the game every hour and press the "free gold" button. You will get 20 gold each time. However, it is still fun to collect extra gold manually, and also to collect stone (without having to buy it).
EMERGENCY UPDATE, 11/03/2018
Xavier Robeldo, the creator of Builder Buddies, has temporarily removed almost all wilderness gold ore. The frequency has been reduced from 16% to 0.3% (ouch!). This was done because of an alleged glitch which he believes is causing people to get an unfair amount of gold. When he fixes the glitch he claims he will restore the 16% (though he has talked about eliminating gold altogether and having in-game ads instead).
In the meantime, if you want to mine gold, try obtaining a plot in an OLD town that was created before the gold reduction. If you dig down in your plot, you will still encounter 16% gold. Or, if you are desperate, go to one of the mines at Diamond Falls. I'm going out of my way to dig out stone chasms at the mines just to uncover a few gold ores that you can harvest the traditional, non-cheating way. First come, first serve so try to be the first one to get them after the wilderness reset. And don't forget free hourly gold all day!
Hopefully Xavier will restore normal mining activities soon. He even has plans for tools you can obtain to make mining faster. We will see what unfolds.
I came up with a way to automatically mine vertically without my having to hold my finger on my iPad. This is actually very difficult because the iPad has a capacitive touch screen which requires some part of the human body to touch it in order to work. I built a box with a fake finger and a conductive wire that attaches at the other end to some part of my body.
Watch YouTube video for instructions and Builder Buddies mining demonstration:
(ADDITIONAL INSTRUCTIONS / CAPTIONS COMING SOON)
Attach the "plug" end to your skin somewhere, such as taping it to your arm or inserting it in your waistband. You can place the box on the iPad to have it start digging, and then while the box continues to "press" the screen on its own, you can get other work done at your desk (write a letter, check Emails, etc.). You can also periodically check the chat window and keep up on the latest town gossip that happened while you were mining.
Besides my own mining activities, I found two other deep pits that people created (prior to publishing my video). Hopefully they also used some sort of automated method, as this represents many game hours of digging!