Rarest Sedimentary Rock — All 39 Answers Ranked by Rarity

39 answers are accepted for “Name a sedimentary rock”. Pelagosite is the rarest sedimentary rock in this ranking, with 401 monthly Wikipedia views (rarity 1.000, Legendary). Biolith is the second-rarest with 473 monthly Wikipedia views, 1.18× the figure for Pelagosite. Coal is the most common sedimentary rock in this ranking, with 286,083 monthly Wikipedia views, 713.4× the figure for the rarest. Combined monthly Wikipedia views across the 39 answers: 1,190,158. Pelagosite is under 0.1% of that total. 8 answers are Epic or Legendary: Pelagosite (Legendary), Biolith (Legendary), Boundstone (Legendary), and 5 more.

Quick answer

Monthly English Wikipedia pageviews. Source: Wikidata + Wikipedia pageviews (2026-10).

Ranked answers

39 answers to “Name a sedimentary rock”, rarest first. A rarity of 1 is the rarest answer in this prompt.
Rank	Answer	Tier	Rarity	Monthly Wikipedia views
1	Pelagosite on Wikipedia	Legendary	1.000	401
2	Biolith on Wikipedia	Legendary	0.974	473
3	Boundstone on Wikipedia	Legendary	0.947	909
4	Rudstone on Wikipedia	Epic	0.921	1,033
5	Pennant Measures on Wikipedia	Epic	0.895	1,068
6	Encrinite on Wikipedia	Epic	0.868	1,161
7	Tasmanite on Wikipedia	Epic	0.842	1,422
8	Tonstein on Wikipedia	Epic	0.816	1,551
9	Lutite on Wikipedia	Rare	0.789	2,024
10	Eolianite on Wikipedia	Rare	0.763	2,394
11	Psammite on Wikipedia	Rare	0.737	2,413
12	Organic-rich sedimentary rocks on Wikipedia	Rare	0.711	2,434
13	Torbanite on Wikipedia	Rare	0.684	2,532
14	Oncolite on Wikipedia	Rare	0.658	3,163
15	Siliceous rock on Wikipedia	Rare	0.632	3,462
16	Beachrock on Wikipedia	Rare	0.605	5,176
17	Source rock on Wikipedia	Uncommon	0.579	6,260
18	Pelite on Wikipedia	Uncommon	0.553	6,273
19	Molasse on Wikipedia	Uncommon	0.526	6,955
20	Radiolarite on Wikipedia	Uncommon	0.500	7,257
21	Rotten stone on Wikipedia	Uncommon	0.474	7,775
22	Red beds on Wikipedia	Uncommon	0.447	8,678
23	Gritstone on Wikipedia	Uncommon	0.421	10,383
24	Thrombolite on Wikipedia	Familiar	0.395	12,128
25	Asphaltite on Wikipedia	Familiar	0.368	15,147
26	Argillite on Wikipedia	Familiar	0.342	17,781
27	Carbonate rock on Wikipedia	Familiar	0.316	18,076
28	Mudstone on Wikipedia	Familiar	0.289	22,402
29	Clastic rock on Wikipedia	Familiar	0.263	23,733
30	Ironstone on Wikipedia	Familiar	0.237	23,756
31	Phosphorite on Wikipedia	Familiar	0.211	30,409
32	Oolite on Wikipedia	Common	0.184	31,218
33	Caliche on Wikipedia	Common	0.158	45,673
34	Tufa on Wikipedia	Common	0.132	49,148
35	Taconite on Wikipedia	Common	0.105	67,207
36	Chalk on Wikipedia	Common	0.079	135,825
37	Stromatolite on Wikipedia	Common	0.053	136,085
38	Bauxite on Wikipedia	Common	0.026	190,290
39	Coal on Wikipedia	Common	0.000	286,083

FAQ

What is the rarest sedimentary rock?

Pelagosite is the rarest sedimentary rock in this ranking, with 401 monthly Wikipedia views (rarity 1.000, Legendary).

How many sedimentary rocks are there?

There are 39 sedimentary rocks in this ranking, from Pelagosite (rarest) to Coal (most common).

What is the most common sedimentary rock?

Coal is the most common sedimentary rock in this ranking, with 286,083 monthly Wikipedia views (Common).

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Sources

Recorded source: Wikidata + Wikipedia pageviews (2026-10). The answer list is compiled from Wikidata (CC0), and the view counts are monthly English Wikipedia pageviews. Rarity is the percentile of the popularity figure inside this prompt: 1 is the rarest and 0 is the most common. Linked names open the English Wikipedia article stored on that answer.