birefringence - 2025 ACF Winter

Question

Answer the following about rutile, or titanium dioxide, for 10 points each.

[10m] Rutile exhibits one of the highest magnitudes of this optical phenomenon for any crystal. This phenomenon, in which materials exhibit two different values of index of refraction, was first observed in calcite crystals.

ANSWER: birefringence [or birefringent]

[10e] Nanoparticles of rutile strongly absorb this radiation, leading it to be used in many sunscreens. Impurities in minerals like calcite and fluorite cause them to glow when exposed to this kind of radiation.

ANSWER: ultraviolet [or UV; accept UV-A or UV-B or UV-C; prompt on blacklight by asking “what type of radiation is emitted by a blacklight?”]

[10h] Rutile is an accessory mineral of this metamorphic rock that consists of garnet and omphacite. The presence of facies of this rock is indicative of ultra-high-pressure metamorphism.

ANSWER: eclogite

<Editors, Other Science>

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Summary


California	Main	Y	4	17.50	75%	100%	0%
Canada	Main	Y	6	20.00	100%	83%	17%
Great Lakes	Main	Y	6	13.33	100%	33%	0%
Lower Mid-Atlantic	Main	Y	7	12.86	100%	29%	0%
Midwest	Main	Y	10	13.00	100%	30%	0%
Northeast	Main	Y	5	14.00	100%	40%	0%
Overflow	Main	Y	4	12.50	100%	25%	0%
Pacific Northwest	Main	Y	10	18.00	100%	80%	0%
South Central	Main	Y	5	14.00	100%	40%	0%
Southeast	Main	Y	12	14.17	100%	42%	0%
UK	Main	Y	4	15.00	100%	50%	0%
Upper Mid-Atlantic	Main	Y	8	15.00	100%	50%	0%
Upstate NY	Main	Y	8	13.75	100%	38%	0%
2024 ARCADIA at UC Berkeley	04/19/2025	Y	1	20.00	100%	100%	0%

Data


Stanford A	Berkeley A	10	10	0	20
Berkeley B	Berkeley E	10	0	0	10
Berkeley D	Berkeley C	10	10	0	20
Stanford B	Stanford C	10	10	0	20
Claremont Scripps	Claremont Pitzer	10	10	0	20
UCLA A	USC	10	10	0	20
UCLA B	UCSD Two Running Violet V Forms	10	10	0	20
UCSD Vices and Virtues	UCLA C	0	10	0	10
UCLA D	UCSB	10	10	0	20
UCI	UCSD What Hath God Wrought	10	10	10	30
ERAU A	ERAU B	0	10	0	10
Melbourne A	FSU	0	10	0	10
UCF A	FIU	10	10	0	20
UF A	UCF B	10	10	0	20
UF B	UF E	0	10	0	10
USF	Melbourne B	0	10	0	10
Pitt B	CWRU D	0	10	0	10
OSU A	OSU D	0	10	0	10
OSU B	CWRU A	0	10	0	10
Pitt A	OSU C	10	10	0	20
Pitt C	Kenyon B	0	10	0	10
James Madison	Liberty B	0	10	0	10
NC State	Roanoke	0	10	0	10
South Carolina B	Virginia B	0	10	0	10
Tennessee A	Virginia Tech A	10	10	0	20
Tennessee B	Tusculum	0	10	0	10
North Carolina B	Virginia A	0	10	0	10
Virginia Tech B	North Carolina C	0	10	0	10
Clemson A	South Carolina A	10	10	0	20
Clemson B	Liberty C	0	10	0	10
Liberty A	North Carolina A	10	10	0	20
MSU B	Kenyon A	0	10	0	10
Swarthmore A	Lehigh B	0	10	0	10
Columbia A	Columbia C	10	10	0	20
Rowan A	Columbia B	0	10	0	10
Rutgers B	Lehigh A	10	10	0	20
Vassar A	Rutgers C	0	10	0	10
Missouri A	WashU A	10	10	0	20
Missouri B	WashU B	0	10	0	10
Truman State	WashU C	0	10	0	10
WashU D	William Woods	0	10	0	10
MSU A	CWRU B	10	10	0	20
Chicago B	UIC	10	10	0	20
Illinois A	Chicago C	10	10	0	20
Illinois B	Kentucky	10	10	0	20
Illinois C	Michigan A	0	10	0	10
Indiana A	Michigan C	10	10	0	20
Louisville B	Indiana B	10	10	0	20
Michigan B	Notre Dame C	10	10	0	20
Michigan D	Notre Dame D	0	10	0	10
Chicago A	Purdue A	10	10	0	20
Louisville A	Purdue B	10	10	0	20
Carleton	Minnesota A	10	10	0	20
Macalester B	Macalester A	0	10	0	10
Minnesota B	Minnesota C	0	10	0	10
Nebraska	Wisconsin	0	10	0	10
BU	Brown C	10	10	0	20
BC B	Bowdoin A	0	10	0	10
Bowdoin B	Amherst B	0	10	0	10
MIT B	Brandeis Clemenceau	10	10	0	20
Tufts A	Brandeis Lloyd George	0	10	0	10
BC A	Brandeis Wilson	0	10	0	10
Brown A	Amherst A	0	10	0	10
Tufts B	Brown B	0	10	0	10
Cornell-UG	Williams	10	10	0	20
Harvard	MIT A	10	10	0	20
Yale A	Dartmouth	10	10	0	20
Yale B	Brandeis Orlando	0	10	0	10
Iowa State	St. Thomas	10	10	0	20
Alberta	British Columbia C	0	10	0	10
Simon Fraser	British Columbia D	10	10	0	20
Washington B	Washington A	10	10	0	20
British Columbia B	British Columbia A	0	10	0	10
Iowa	Northwestern C	0	10	0	10
Alberta B	McGill D	10	10	0	20
Arizona State A	Northwestern A	10	10	0	20
Northwestern B	Texas A	0	10	0	10
Ohio	UTD B	0	10	0	10
Rose State	Tulsa	10	10	0	20
Texas B	UCO	0	10	0	10
UTD A	Arizona State B	10	10	0	20
Bruin A	Georgia Tech B	0	10	0	10
Auburn B	Mississippi State A	0	10	0	10
Georgia Tech A	Vanderbilt A	10	10	0	20
Huntsville B	Alabama B	0	10	0	10
Alabama A	Sewanee A	0	10	0	10
Huntsville A	UAB A	0	10	0	10
Auburn A	Vanderbilt B	10	10	0	20
Georgia Tech D	Georgia Tech C	10	10	0	20
RIT B	Cornell-DII	10	10	0	20