Over the weekend I lost a battle with a cairn. Or at least my finger did. I was over in Leavenworth to give a talk to the fine folks of the Wenatchee River Institute and the Barn Beach Reserve. It was a great event with about 70-75 people attending. They were definitely a hiking crowd with many quite familiar with cairns, particularly in their own backyard of the Enchantments. On Saturday we regathered for a cairn building session on the Barn Beach property. A trail passes through the area and the cairns would help direct people from one trail segment to another. 
We began by collecting rocks from several nearby rock piles. It was good rock: blocks of granite with rough surfaces. We then picked a conspicuous location, as discussed in my book, a began to build the pile, always seeking to provide enough batter for stability. It was during this part of the cairn building that my finger was wounded. I distinctly remember thinking that I needed to avoid crushing my right hand when placing the rock I carried. I was successful there but unfortunately I omitted to notice that my left hand, and in particular my pointing finger, was about to be placed between a rock and a hard place. The result is below. Rather ugly but much less painful than it looks.
So now I need to add one more line to my presentation about how to build a cairn. Remember you have two hands and need to watch out for both of them. It’s never to late to learn.
Stories left untold when talking to one’s mother.
Oof Da. Sorry to hear you were wounded in action. I was going to offer to bring one of my trebuchets if you wanted to renew your battle with that cairn, but on reflection I think it wouldn’t be a good idea, as all my trebs are miniature ones and would only be effective against miniature cairns. Which I might start using for practice.
Thank you for bringing my attention to the geological wonders all around us. What is that stuff that the Bon/Macy’s in Seattle is faced with at ground level, that looks kind of like red granite but has bits of clear stuff in it that flash pale, iridescent blue?
Thanks for your note and concern about my finger. It’s healing well. I know the rock of which you speak but have no clue where it is from or exactly what it is. I am pretty sure that the blue iridescent minerals are labradorite, a type of feldspar, usually found in mafic (iron and magnesium rich) rocks such as gabbro and basalt. I wish I knew more. Sorry.