The new mineral libbyite (IMA2022-091), (NH4)2(Na2□)[(UO2)2(SO4)3(H2O)]2⋅7H2O, was found in the Blue Lizard mine, San Juan County, Utah, USA, where it occurs as tightly intergrown aggregates of light green–yellow equant crystals in a secondary assemblage with bobcookite, coquimbite, halotrichite, metavoltine, rhomboclase, römerite, tamarugite, voltaite and zincorietveldite. The streak is very pale green yellow and the fluorescence is strong green under 405 nm ultraviolet light. Crystals are transparent with vitreous lustre. The tenacity is brittle, the Mohs hardness is ~2½, the fracture is curved. The mineral is soluble in H2O and has a calculated density of 3.465 g⋅cm–3. The mineral is optically uniaxial (–) with ω = 1.581(2) and ɛ = 1.540(2). Electron microprobe analyses provided (NH4)1.92K0.08Na2.00U4.00S6.00O41H18.00. Libbyite is tetragonal, P41212, a = 10.7037(11), c = 31.824(2) Å, V = 3646.0(8) Å3 and Z = 4. The structural unit is a uranyl–sulfate sheet that has the same topology as the sheets in several synthetic uranyl selenates.

The new mineral zincorietveldite (IMA2022-070), Zn(UO2)(SO4)2(H2O)5, was found in the Blue Lizard mine, San Juan County, Utah, USA, where it occurs as yellow to orange–yellow blades in a secondary assemblage with bobcookite, coquimbite, halotrichite, libbyite, metavoltine, rhomboclase, römerite, tamarugite and voltaite. The streak is very pale yellow. Crystals are transparent with vitreous lustre. The tenacity is brittle, the Mohs hardness is ~2½ and the fracture is curved. Cleavage is excellent on {010}, good on {100} and fair on {001}. The mineral is easily soluble in H2O and has a calculated density of 3.376 g⋅cm–3. The mineral is optically biaxial (+) with α = 1.568(2), β = 1.577(2) and γ = 1.595(2); 2V = 70(1)°. Electron microprobe analyses provided (Zn0.720Mg0.109Fe0.091Mn0.046Co0.035)Σ1.00(UO2)(SO4)2(H2O)5. Zincorietveldite is orthorhombic, Pmn21, a = 12.8712(9), b = 8.3148(4), c = 11.2959(4) Å, V = 1208.90(11) Å3 and Z = 4. Zincorietveldite is the Zn analogue of rietveldite. The structural unit is a uranyl-sulfate chain that is also found in the structures of bobcookite, oldsite, oppenheimerite and svornostite.

The new mineral shinarumpite (IMA2021-105), [Co(H2O)6][(UO2)(SO4)2(H2O)]⋅4H2O, was found in the Scenic mine on Fry Mesa, White Canyon district, San Juan County, Utah, USA, where it occurs as a secondary phase on granular quartz matrix in association with gypsum, deliensite, Co-rich rietveldite, scenicite, shumwayite and sulfur. Shinarumpite crystals are transparent, yellow, blades or prisms, up to 1 mm in length. The mineral has white streak, vitreous lustre and is nonfluorescent. It is brittle with irregular, curved fracture. The Mohs hardness is ~2½ and it has a perfect {100} cleavage. The density is 2.58(2) g⋅cm–3. Optically, the mineral is biaxial (–) with α = 1.515(2), β = 1.526(2), γ = 1.529(2) (white light); 2V = 55(1)°; extreme r < v dispersion; orientation: Z = b, X ^ a = 30° in obtuse β; pleochroism: X = very pale yellow, Y = pale yellow, Z = light yellow; X < Y < Z. The Raman spectrum exhibits bands consistent with UO22+, SO42– and O–H. Electron microprobe analysis provided the empirical formula [(Co0.51Ni0.28Fe0.21)Σ1.00(H2O)6][(UO2)(SO4)2(H2O)]⋅4H2O. The five strongest powder X-ray diffraction lines are [dobs Å(I)(hkl)]: 10.37(100)(200), 5.73(43)(111), 5.20(70)(400, 202, 211), 4.70(31)($\bar{3}$11) and 3.326(30)(213, 021). Shinarumpite is monoclinic, P21/c, a = 21.0549(15), b = 6.8708(5), c = 12.9106(5), β = 96.678(7)°, V = 1885.03(17) Å3 and Z = 4. In the structure of shinarumpite (R1 = 0.0336 for 2623 I > 2σI), linkages of pentagonal bipyramids and tetrahedra form an infinite [(UO2)(SO4)2(H2O)]2– sheet. Isolated Co(H2O)6 octahedra and H2O groups occupy the interlayer region linking the sheets via an extensive system of hydrogen bonds. The structure of shinarumpite is very similar to that of leydetite. Uranyl sulfate structural unit types are discussed with respect to frequency and charge deficiency per anion (CDA).

The new mineral scenicite (IMA2021-057), [(UO2)(H2O)2(SO4)]2⋅3H2O, was found in the Green Lizard, Giveaway–Simplot, Markey and Scenic mines, White Canyon district, San Juan County, Utah, USA, where it occurs as a secondary phase on granular quartz matrix in association with various combinations of deliensite, gypsum, natrozippeite, rietveldite and shumwayite. Scenicite crystals are transparent, light green yellow, poorly formed blades or prisms, up to 0.1 mm in length. The mineral has white streak and vitreous lustre. It exhibits bright greenish-white fluorescence (405 nm laser). It is brittle with irregular, curved fracture and a Mohs hardness of ~2. It has excellent {100} and good {001} cleavages. The calculated density is 3.497 g cm–3. Optically, the mineral is biaxial (–) with α = 1.556(2), β = 1.573(2), γ = 1.576(2) (white light); 2V = 45(3)°; extreme r < v dispersion; orientation: X = c, Y = a, Z = b; pleochroism: X and Y = colourless, Z = light green–yellow; and X = Y < Z. The Raman spectrum exhibits bands consistent with UO22+, SO42– and O–H. Electron microprobe analysis provided the empirical formula U1.996S2.005O19H13.997. The five strongest powder X-ray diffraction lines are [dobs Å(I)(hkl)]: 7.69(70)(201), 5.63(100)(111), 4.92(84)(202,310), 4.80(93)(401) and 3.398(55)(020,120,511,601). Scenicite is orthorhombic, Pca21, a = 21.2144(15), b = 6.8188(3) c = 11.2554(6) Å, V = 1628.18(16) Å3 and Z = 4. In the structure of scenicite (R1 = 0.0365 for 1259 I > 2σI), linkages of pentagonal bipyramids and tetrahedra form an infinite neutral [(UO2)(SO4)(H2O)2] chain. The structure of shumwayite contains topologically identical chains.

The new mineral paramarkeyite (IMA2021-024), Ca2(UO2)(CO3)3⋅5H2O, was found in the Markey mine, San Juan County, Utah, USA, where it occurs as a secondary phase on gypsum-coated asphaltum in association with andersonite, calcite, gypsum and natromarkeyite. Paramarkeyite crystals are transparent, pale green-yellow, striated tablets, up to 0.11 mm across. The mineral has white streak and vitreous lustre. It exhibits moderate bluish-white fluorescence (405 nm laser). It is very brittle with irregular, curved fracture and a Mohs hardness of 2½. It has an excellent {100} cleavage and probably two good cleavages on {010} and {001}. The measured density is 2.91(2) g cm–3. Optically, the mineral is biaxial (–) with α = 1.550(2), β = 1.556(2), γ = 1.558(2) (white light); 2V = 60(2)°; strong r > v dispersion; orientation: Y = b; nonpleochroic. The Raman spectrum exhibits bands consistent with UO22+, CO32– and O–H. Electron microprobe analysis provided the empirical formula (Ca1.83Na0.20Sr0.03)Σ2.05(UO2)(CO3)3⋅5H2O (+0.07 H). Paramarkeyite is monoclinic, P21/n, a = 17.9507(7), b = 18.1030(8), c = 18.3688(13) Å, β = 108.029(8)°, V = 5676.1(6) Å3 and Z = 16. The structure of paramarkeyite (R1 = 0.0647 for 6657 I > 2σI) contains uranyl tricarbonate clusters that are linked by Ca–O polyhedra to form heteropolyhedral layers. The structure of paramarkeyite is very similar to those of markeyite, natromarkeyite and pseudomarkeyite.

Jeankempite, Ca5(AsO4)2(AsO3OH)2(H2O)7, is a new mineral species (IMA2018-090) discovered amongst coatings of arsenate minerals on oxidised copper arsenides from the Mohawk No. 2 mine, Mohawk, Keweenaw County, Michigan, USA. The new mineral occurs as lamellar bundles of colourless to white plates up to 1 mm wide and is visually indistinguishable from guérinite, with which it forms intergrowths. Jeankempite is transparent to translucent with a waxy lustre and white streak, is non-fluorescent under longwave and shortwave ultraviolet illumination, has a Mohs hardness of ~1.5 and brittle tenacity with uneven fracture. Crystals are flattened on {01$\bar{1}$} and exhibit perfect cleavage on {01$\bar{1}$}. Optically, jeankempite is biaxial (+), α = 1.601(2), β = 1.607(2), γ = 1.619(2) (white light); 2Vmeas. = 72(2)° and 2Vcalc. = 71.0°. The empirical formula is (Ca4.97Na0.013Mg0.017)(As3.99S0.01)4O23H16, based on 23 O and 16 H atoms per formula unit. Thermogravimetric analysis indicates that jeankempite undergoes four weight losses totalling 16.82%, close to the expected loss of 16.30%, corresponding to eight H2O. Jeankempite is triclinic, P$\bar{1}$, a = 6.710(6), b = 14.901(14), c = 15.940(15) Å, α = 73.583(12)°, β = 81.984(12)°, γ = 82.754(12)°, V = 1507(2) Å3 and Z = 3. The final structure was refined to R1 = 0.0591 for 2781 reflections with Iobs > 3σI. The crystal structure of jeankempite is built from a network of edge- and vertex-sharing CaO6, CaO7 and AsO4 polyhedra, and we hypothesise that the new mineral has formed due to a topotactic reaction brought on by dehydration of preexisting guérinite.

The new minerals natromarkeyite, Na2Ca8(UO2)4(CO3)13(H2O)24⋅3H2O (IMA2018-152) and pseudomarkeyite, Ca8(UO2)4(CO3)12(H2O)18⋅3H2O (IMA2018-114) were found in the Markey mine, San Juan County, Utah, USA, where they occur as secondary phases on asphaltum. Natromarkeyite properties are: untwinned blades and tablets to 0.2 mm, pale yellow green colour; transparent; white streak; bright bluish white fluorescence (405 nm laser); vitreous to pearly lustre; brittle; Mohs hardness 1½ to 2; irregular fracture; three cleavages ({001} perfect, {100} and {010} good); density = 2.70(2) g cm–3; biaxial (–) with α = 1.528(2), β = 1.532(2) and γ = 1.533(2); and pleochroism is X = pale green yellow, Y ≈ Z = light green yellow. Pseudomarkeyite properties are: twinned tapering blades and tablets to 1 mm; pale green yellow colour; transparent; white streak; bright bluish white fluorescence (405 nm laser); vitreous to pearly lustre; brittle; Mohs hardness ≈ 1; stepped fracture; three cleavages ({10$\bar{1}$} very easy, {010} good, {100} fair); density = 2.88(2) g cm–3; biaxial (–) with α = 1.549(2), β = 1.553(2) and γ = 1.557(2); and it is nonpleochroic. The Raman spectra of markeyite, natromarkeyite and pseudomarkeyite are very similar and exhibit bands consistent with UO22+, CO32– and O–H. Electron microprobe analyses provided the empirical formula Na2.01Ca7.97Mg0.03Cu2+0.05(UO2)4(CO3)13(H2O)24⋅3H2O (–0.11 H) for natromarkeyite and Ca7.95(UO2)4(CO3)12(H2O)18⋅3H2O (+0.10 H) for pseudomarkeyite. Natromarkeyite is orthorhombic, Pmmn, a = 17.8820(13), b = 18.3030(4), c = 10.2249(3) Å, V = 3336.6(3) Å3 and Z = 2. Pseudomarkeyite is monoclinic, P21/m, a = 17.531(3), b = 18.555(3), c = 9.130(3) Å, β = 103.95(3)°, V = 2882.3(13) Å3 and Z = 2. The structures of natromarkeyite (R1 = 0.0202 for 2898 I > 2σI) and pseudomarkeyite (R1 = 0.0787 for 2106 I > 2σI) contain uranyl tricarbonate clusters that are linked by (Ca/Na)–O polyhedra forming thick corrugated heteropolyhedral layers. Natromarkeyite is isostructural with markeyite; pseudomarkeyite has a very similar structure.

The new mineral uranoclite (IMA2020-074), (UO2)2(OH)2Cl2(H2O)4, was found in the Blue Lizard mine, San Juan County, Utah, USA, where it occurs as tightly intergrown aggregates of irregular yellow crystals in a secondary assemblage with gypsum. The streak is very pale yellow and the fluorescence is bright green–white under 405 nm ultraviolet light. Crystals are translucent with vitreous lustre. The tenacity is brittle, the Mohs hardness is ~1½, the fracture is irregular. The mineral is soluble in H2O and has a calculated density of 4.038 g⋅cm–3. Electron microprobe analyses provided (UO2)2(OH)2.19Cl1.81(H2O)4. The six strongest powder X-ray diffraction lines are [dobs Å(I)(hkl)]: 8.85(38)(002), 5.340(100)(200, 110), 5.051(63)($\bar{2}$02), 4.421(83)(112, 004, 202), 3.781(38)($\bar{2}$12) and 3.586(57)(014, $\bar{2}$04). Uranoclite is monoclinic, P21/n, a = 10.763(8), b = 6.156(8), c = 17.798(8) Å, β = 95.656(15)°, V = 1173.5(18) Å3 and Z = 4. The structure is the same as that of synthetic (UO2)2(OH)2Cl2(H2O)4 in which the structural unit is a dimer consisting of two pentagonal bipyramids that share an equatorial OH–OH edge. The dimers are linked to one another only by hydrogen bonding. This is the second known uranyl mineral containing essential Cl and the first in which Cl coordinates to U6+.

The new mineral pseudomeisserite-(NH4) (IMA2018-166), (NH4,K)2Na4[(UO2)2(SO4)5]⋅4H2O, was found in the Blue Lizard mine, San Juan County, Utah, USA, where it occurs as light yellow prisms in a secondary assemblage with belakovskiite, blödite, changoite, ferrinatrite, gypsum, ivsite, metavoltine and tamarugite. The streak is very pale yellow and the fluorescence is bright lime green under 405 nm ultraviolet light. Crystals are transparent with vitreous lustre. The tenacity is brittle, the Mohs hardness is 2½, the fracture is curved or conchoidal and there is one perfect cleavage on {100}. The mineral is easily soluble in H2O and has a measured density of 3.22(2) g⋅cm–3. Pseudomeisserite-(NH4) is optically biaxial (–) with α = 1.536(2), β = 1.559(2) and γ = 1.565(2) (white light); 2Vmeas. = 53(1)°; dispersion is r > v, distinct; pleochroism: X colourless, Y light yellow and Z pale yellow (X < Z < Y); optical orientation: Z = b, Y ∧ c = 33° in obtuse β). Electron microprobe analyses (WDS mode) provided (NH4)1.49K0.60Na3.87U2.00S5.04O28H7.78. The five strongest X-ray powder diffraction lines are [dobs, Å(I)(hkl)]: 12.69(76)(100), 6.83(84)(012,102), 6.01(100)($\bar{2}$02), 3.959(67)($\bar{2}$21,$\bar{2}$14,$\bar{1}$23) and 3.135(76)($\bar{2}$06,223,$\bar{1}$16). Pseudomeisserite-(NH4) is monoclinic, P21/c, a = 13.1010(3), b = 10.0948(2), c = 19.4945(14) Å, β = 104.285(7)°, V = 2498.5(2) Å3 and Z = 4. The structural unit in the structure (R1 = 0.0254 for 3837 I > 2σI reflections) is a novel [(UO2)2(SO4)5]6– uranyl-sulfate band.

The new mineral lussierite (IMA2018-101), Na10[(UO2)(SO4)4](SO4)2(H2O)3, was found in the Blue Lizard mine, San Juan County, Utah, USA, where it occurs as pale green–yellow prisms or blades in a secondary assemblage with belakovskiite, ferrinatrite, halite, ivsite, metavoltine and thénardite. The streak is white and the fluorescence is bright cyan under 365 nm ultraviolet light. Crystals are transparent with vitreous lustre. The tenacity is brittle, the Mohs hardness is 2½, the fracture is irregular and no cleavage was observed. The mineral is easily soluble in H2O and has a measured density of 2.87(2) g cm–3. Lussierite is optically biaxial (+), with α = 1.493(1), β = 1.505(1) and γ = 1.518(1) (white light); 2Vmeas. = 88(1)°; dispersion is r > v, moderate; pleochroism: X = colourless, Y and Z = green yellow (X < Y ≈ Z); optical orientation: X = b, Z ∧ a = 44° in obtuse β. Electron microprobe analyses (wavelength-dispersive spectroscopy mode) provided Na10(U0.99O2)(S1.00O4)6·3H2O (+0.06 H for charge balance). The five strongest X-ray powder diffraction lines are [dobs Å(I)(hkl)]: 6.69(95)($\bar{1}$11,130), 4.814(100)(150,002,060), 3.461(83)(171,$\bar{2}$02), 2.955(81)(113,330) and 2.882(74)($\bar{1}$91,311,191,0·10·0). Lussierite is monoclinic, Cc, a = 9.3134(4), b = 28.7501(11), c = 9.6346(7) Å, β = 93.442(7)°, V = 2575.1(2) Å3 and Z = 4. The structure (R1 = 0.0298 for 5202 I > 2σI) contains a [(UO2)(SO4)4]6– uranyl sulfate cluster in which one SO4 tetrahedron shares an edge (bidentate linkage) with the UO7 pentagonal bipyramid. The uranyl sulfate clusters occur in layers and are linked through a complex network of bonds involving Na+ cations, isolated SO4 tetrahedra and isolated H2O groups.

The new mineral feynmanite, Na(UO2)(SO4)(OH)·3.5H2O, was found in both the Blue Lizard and Markey mines, San Juan County, Utah, USA, where it occurs as a secondary phase on pyrite-rich asphaltum in association with chinleite-(Y), gypsum, goethite, natrojarosite, natrozippeite, plášilite, shumwayite (Blue Lizard) and wetherillite (Markey). The mineral is pale greenish yellow with a white streak and fluoresces bright greenish white under a 405 nm laser. Crystals are transparent with a vitreous lustre. It is brittle, with a Mohs hardness of ~2, irregular fracture and one perfect cleavage on {010}. The calculated density is 3.324 g cm–3. Crystals are thin needles or blades, flattened on {010} and elongate on [100], exhibiting the forms {010}, {001}, {101} and {10$\bar{1}$}, and are up to ~0.1 mm in length. Feynmanite is optically biaxial (–), with α = 1.534(2), β = 1.561(2) and γ = 1.571(2) (white light); 2Vmeas. = 62(2)°; no dispersion; and optical orientation: X = b, Y ≈ a,Z ≈ c. It is weakly pleochroic: X = colourless, Y = very pale green yellow and Z = pale green yellow (X < Y < Z). Electron microprobe analyses (WDS mode) provided (Na0.84Fe0.01)(U1.01O2)(S1.01O4)(OH)·3.5H2O. The five strongest powder X-ray diffraction lines are [dobs Å(I)(hkl)]: 8.37(100)(010), 6.37(33)($\bar{1}$01,101), 5.07(27)($\bar{1}$11,111), 4.053(46)(004,021) and 3.578(34)(120). Feynmanite is monoclinic, has space group P2/n, a = 6.927(3), b = 8.355(4), c = 16.210(7) Å, β = 90.543(4)°, V = 938.1(7) Å3 and Z = 4. The structure of feynmanite (R1 = 0.0371 for 1879 Io > 2σI) contains edge-sharing pairs of pentagonal bipyramids that are linked by sharing corners with SO4 groups, yielding a [(UO2)2(SO4)2(OH)2]2– sheet based on the phosphuranylite anion topology. The sheet is topologically identical to those in deliensite, johannite and plášilite. The dehydration of feynmanite to plášilite results in interlayer collapse involving geometric reconfiguration of the sheets and the ordering of Na.

Redcanyonite (IMA2016-082), (NH4)2Mn[(UO2)4O4(SO4)2](H2O)4, occurs underground in the Blue Lizard mine, Red Canyon, White Canyon district, San Juan County, Utah, USA. It occurs with natrozippeite, brochantite, devilline, posnjakite, johannite, gypsum, bobcookite, pickeringite, pentahydrite and the NH4-analogue of zippeite: ammoniozippeite. Redcanyonite occurs as radial aggregates of red–orange needles and blades individually reaching up to 0.2 mm long, with aggregates measuring up to 1 mm in diameter. Crystals are flattened on {010} and elongated along [100], exhibit perfect cleavage on {010}, and exhibit the forms {010}, {001}, {101} and {10$\bar{1}$}. Twinning is ubiquitous, by 180° rotation on [100]. Redcanyonite is translucent with a pale orange streak, is non-fluorescent, has a Mohs hardness of 2, and has brittle tenacity with uneven fracture. Optically, redcanyonite is biaxial (+), α = 1.725(3), β = 1.755(3), γ = 1.850(5) (white light); 2V (meas.) = 60(2)°, 2V (calc.) = 61.3°; and dispersion is r < v, very strong. Pleochroism is: X = orange, Y = yellow and Z = orange; Y << X < Z. The optical orientation is X = b, Y ≈ c*, Z ≈ a. The empirical formula is (NH4)2.02(Mn0.49Cu0.09Zn0.06)Σ0.64H+0.72[(UO2)4O4(S0.99P0.01O4)2](H2O)4, based on 4 U and 24 O apfu. Redcanyonite is monoclinic, C2/m, a = 8.6572(17), b = 14.155(3), c = 8.8430(19) Å, β = 104.117(18)°, V = 1050.9(4) Å3 and Z = 2. The structure was refined to R1 = 0.0382 for 1079 reflections with Iobs > 3σI. Uranyl oxo-sulfate sheets in redcanyonite adopt the well-known zippeite topology, which consists of zigzag chains of uranyl pentagonal bipyramids linked by sulfate tetrahedra to form sheets. The sheets are linked to each other through bonds to interlayer NH4+ groups and octahedrally coordinated Mn2+, and by hydrogen bonds from H2O groups. Redcanyonite is named for Red Canyon in southeast Utah, USA.

Leószilárdite (IMA2015-128), Na6Mg(UO2)2(CO3)6·6H2O, was found in the Markey Mine, Red Canyon, White Canyon District, San Juan County, Utah, USA, in areas with abundant andersonite, natrozippeite, gypsum, anhydrite, and probable hydromagnesite along with other secondary uranium minerals bayleyite, čejkaite and johannite. The new mineral occurs as aggregates of pale yellow bladed crystals flattened on ﹛001﹜ and elongated along [010], individually reaching up to 0.2 mmlong. More commonly it occurs as pale yellow pearlescent masses to 2 mm consisting of very small plates. Leószilárdite fluoresces green under both longwave and shortwave ultraviolet light, and is translucent with a white streak, hardness of 2 (Mohs), and brittle tenacity with uneven fracture. The new mineral is readily soluble in room temperature H2O. Crystals have perfect cleavage along ﹛001﹜, and exhibit the forms ﹛110﹜,﹛001﹜,﹛100﹜,﹛101﹜ and ﹛101﹜. Optically, leószilárdite is biaxial (-), α= 1.504(1), β= 1.597(1), γ= 1.628(1) (white light); 2V (meas.) = 57(1)°, 2V (calc.) = 57.1°; dispersion r > v, slight. Pleochroism: X= colourless, Y and Z= light yellow; X<Y ≈ Z The average of six wavelength dispersive spectroscopic analyses provided Na2O 14.54, MgO 3.05, UO3 47.95, CO2 22.13, H2O 9.51, total 97.18 wt.%. The empirical formula is Na5.60Mg0.90U2O28C6H12.60, based on 28 O apfu. Leószilárdite is monoclinic, C2/m, a = 11.6093(21), b = 6.7843(13), c = 15.1058(28) Å, β = 91.378(3)°, V= 1189.4(4) Å3 and Z = 2. The crystal structure (R1 = 0.0387 for 1394 reflections with Iobs > 4σI), consists of uranyl tricarbonate anion clusters [(UO2)(CO3)3]4- held together in part by irregular chains of NaO5(H2O) polyhedra sub parallel to [010]. Individual uranyl tricarbonate clusters are also linked together by three-octahedron units consisting of two Na-centred octahedra that share the opposite faces of a Mg-centred octahedron at the centre (Na–Mg–Na), and have the composition Na2MgO12(H2O)4. The name of the new mineral honours the Hungarian-American physicist, inventor and biologist Dr. Leó Szilárd (1898–1964).