Talk:Crystal Shard

Light
Proof that they light up http://cloud.steampowered.com/ugc/613844717629948027/F26CA80D6E8B37756AE1B5762DAB9F83BA5D6642/ - 71.87.116.224 02:22, 7 December 2011 (UTC)
 * Oh, my mistake. It's because I was using a different lighting mode during my gameplay. I forgot about that. 98.117.189.194 03:44, 7 December 2011

Correct dimensions?
Is the dimension of 2x2 correct? 141.157.176.90 20:29, 14 December 2011 (UTC)
 * Nope. Fixed. --Manxome 20:42, 14 December 2011 (UTC)

Spawn requirements
Does the world have to be in hardmode for crystal shards to spawn? My tests seem to indicate so, but I could be just unlucky and the page doesn't have information to this respect. --190.55.92.154 02:38, 22 December 2011 (UTC)

I have a world in which crystal shards are occurring in the Underground layer - just above the Cavern layer (within screen size of it), but clearly in the Underground layer. Has anyone else seen this? Wizarth 12:06, 20 January 2012 (UTC)

To answer both of the above, shards can grow pre and post hardmode. Shards grow the most nearest to hell and the least towards surface, further less in pre-hardmode. Shards need both space and an adjacent (top, left, or right) pearlstone block. It is tested that having all three adjacent is faster only because of connectable points however it is highly inefficient space-wise. Please check the forums for some of these answers specifically the thread devoted to finding the best farming method of shards, which is where I gotten this info (and I might be "slightly" outdated). 98.133.93.231 18:33, 20 January 2012 (UTC)

On this topic, can the crystals spawn when there's a wall behind them? I was just thinking of making a farm, and I'd prefer if monsters couldn't spawn inside. 98.246.78.132 02:50, 18 June 2012 (UTC)


 * I have, through experimentation, Confirmed that crystal shards will grow in front of a placed wall :) 67.161.7.31 22:08, 28 June 2013


 * Where is that farming guide? I'm wondering whether the crystals spawn "on a pearlstone block", or "in space next to a pearlstone block".  That is, will the separated-blocks farm be faster or slower than solid rows? --MentalMouse42 (talk) 14:26, 3 October 2017 (UTC)
 * I believe you're looking for Guide:Renewable Resources. Crystal Shards grow on open surfaces of Pearlstone/Pink Ice. A single free-floating Pearlstone Block could grow 4 crystals (one on each open surface). – Ferretwings (talk ) 20:24, 3 October 2017 (UTC)
 * Um no, that's a one-sentence placeholder. I was looking for the forum article that IP:98.133.93.231 mentioned (I tried searching there, with no luck), in hopes that they would have done rate-testing.  Basically, my question is whether on each pass, the game is checking each pearlstone block to see if it should add an adjacent crystal, or each empty space to see if it could grow a crystal (or, presumably, something else).  Barring more complex adjacency checks (say, like Minecraft wheat crops), in the former case isolated blocks would grow slower even if they max out at more crystals per stone block.  In the latter case, solid layers would grow slower (less eligible space).  Either way the solid layers max out with more crystals per length of layer (6/3 blocks versus 4/1 block each 3 spaces), but I doubt I'd ever wait that long for harvest. --MentalMouse42 (talk) 00:14, 4 October 2017 (UTC)
 * Well, considering how old this discussion is, original poster is unlikely to notice. Also because of that, the thread you're looking for is probably on the old terrariaonline forums, which are gone, and afaik weren't properly archived(you can try your luck with archive.org of www.terrariaonline.com/forums/). Anyway, this could be wrong, but basically, each tick game picks a lot of random tiles and tries to do an update on them. If that tile happens to be pearlstone or pink ice, and it's in caverns layer or below(and passes a random roll for 1/110), it picks a random spot to one of it's four sides(top/bottom/left/right). There seems to be a bug that prevents it selecting top side(although it seems that if crystal spawns on the bottom, and there's another block below it, it will look like it's growing from top of the bottom block), so odds are 2/4 for bottom, 1/4 left and 1/4 for right side. If that spot is not occupied by another tile, it counts amount of crystal shards in a 13x13 square centered on the initial hallowed block position. If it's less than 2, it spawns a new crystal shard at the adjacent position it picked earlier. There are not re-rolls if something fails at any stage. As for optimal farming, I'd personally go with horizontal rows, just to have more blocks for a random world update to land on, but I have no math or statistics to back it up.
 * Thank you! That's very helpful, and if things still work that way, it means that solid rows will indeed be much faster, but the maximum yield for a harvest is capped way below the apparent packing capacity for either setup.  Of course, solid rows also will need three times as many actuators.  Now I'm thinking the way to go would be blocks, but perhaps with a day and/or night sensor to regularly tap the harvest.  Of course, that could cause problems with excessive item buildup.... --MentalMouse42 (talk) 01:02, 5 October 2017 (UTC)
 * ETA: On experimentation, I think setting up blocks and actuators every three spaces is picky and slow enough to warrant the extra cost for solid rows. --MentalMouse42 (talk) 02:37, 5 October 2017 (UTC)

There seems to be a non-obvious depth threshold for spawning
With my initial farm, I noticed that the top rows weren't spawning anything, while the bottom ones did. Looking around confirms that there is a line, which does not seem to be the Underground/Caverns line or anything else obvious. I'll try to get the exact height after my current boss-fight, but it was about halfway up the central hollow of the former Crimson Chasm that I'm working around. --MentalMouse42 (talk) 13:25, 6 October 2017 (UTC)
 * Interesting... I never noticed that until I tested just now. I wish you luck in finding the depth —ϟAwesome_Diamondsϟ (talk) 13:58, 6 October 2017 (UTC)
 * Well, in-game uses Main.rockLayer which I kind of assumed was the border between underground and caverns. After looking at the depth meter code, and some confusion, it seems that depth meter starts showing caverns when you're 38-40 blocks under rockLayer(unless I'm still confused which way the difference goes). Anyway, screenshots with depth information at underground and caverns would help. Good thing I put that "this could be wrong" above :p 86.115.19.146 14:44, 6 October 2017 (UTC)
 * Checking the depth in my small world, the highest crystals I found were at 225 underground, which is about 30 blocks below the wiki-listed border. --MentalMouse42 (talk) 16:33, 6 October 2017 (UTC)
 * Did you mean above, since it's still underground? Started up the game and built a tiny farm to verify. Got crystal shard to grow above the underground/caverns border, didn't bother testing how high above the border it would grow, but should be around 40 blocks(don't see a real need to test or examine the code for exact border). Results at https://imgur.com/a/ZB32X 86.115.19.146 16:45, 6 October 2017 (UTC)

Size-optimal shard farm
So, I have managed to mathematically prove that laying pearlstone in a checkerboard pattern (with actuators, see screenshot) is the most space-efficient shard farm layout. I could elaborate if anyone is interested, but the basic idea is that this pattern achieves maximum pearlstone density (50%) while keeping open spaces to all sides of every block (100%). Since the growing algorithm first picks a random block and then picks a random direction, the chance to grow a shard is proportional to the product of those two percentages. And it can be shown that any attempt to increase stone density will reduce neighboring open spaces such that the product will decline. Thus, checkerboard is optimal. This is valid both discounting and accounting for the downwards-instead-of-upwards bug, although in the latter case the proof is a bit more complicated.

However, it turns out that building such a farm is incredibly tedious! In the time I placed and wired the rectangle in the screenshot, I could probably have excavated a much larger area and quickly have filled it with pearlstone rows. Since free space and pearlstone are usually much less a limiting factor than the player's effort, I must regretfully conclude that in practice one should probably stick to simple rows or maybe columns of pearlstone. 176.193.134.193 19:31, 3 March 2018 (UTC)
 * Sounds like a great farm, feel free to put this on the page —ϟ Awesome_Diamonds ϟ 「talk」 22:39, 3 March 2018 (UTC)
 * It's really not, that was my entire point. I spend over an hour building it, and it only gives out 20-30 shards per harvest!  It may be advanced and pretty, but it's still impractical.  Rows are definitely the way to go.  One improvement that may actually be worthwhile is to place a row of ebonstone above each pearlstone row.  They will cancel each other out, preventing Hallow enemies from spawning, and since shards don't grow upwards, it won't impact the farm's perfomance.  I should try that sometime.  176.193.134.193 19:31, 8 March 2018 (UTC)